741
AWIO20 FMEE 061138

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/06 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is now scattered over our basin and is still locally maintained close to the now remnant low that has been followed for the last few days over the Northeastern basin.

Remnant low east of Diego-Garcia:

A strong east-north-east vertical shear coupled with dry air intrusions from subtropical origin have impeded the developing trend observed 48 hours ago. At 11Z this low is located around 7.8oS and 77.4oE. It moves slowly westward at 5-8 kt. The central pressure is estimated at 1005 hPa and winds are light at 10/15 kt.

Over the next few days, this system will accelerate in a general westerly direction in an environment that is still sheared and without potential for intensification. It should dissipate in the second part of the week over the South of the Seychelles Archipelago.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

424
AWIO20 FMEE 081155

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/08 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Deep convection is still present on our basin, near two clockwise circulations within a near equatorial trough becoming ill defined.

Remnant low west of Diego-Garcia:

Last observations show the presence of a closed circulation near 7.5S/67.0E at 10Z moving west-south-westerly. Maximum winds are estimated around 15kt in the northern semi-circle and 25kt and the southern. Convective activity is undergoing the influence of a strong vertical wind shear (30kt North-Easterly). This upper constraint iin relation with dry air is still preventing the development of the low. Given this context, the low is expected to fill up by the end of the week while moving westward towards th
e Seychelles.

In the far east of the basin :

A surface trough can be located in the latest ASCAT data between 85 and 90E and between 2 and 4S. Convective activity is moderate to strong which favored the building of the trough. This low is not expected to intensify because of its current proximity to the equator and then at longer range due to the presence of a moderate northeasterly wind shear and a lack of equatorial convergence in relation with the upturn northward of the equatorial westerlies.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

521
AWIO20 FMEE 091011

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/09 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity remains in our basin, close to a low-pressure circulation within a near-equatorial trough.

Remnant low east of Coetivy:

The last observations show the persistence of a large circulation located around 6.5S/61.3E moving west-southwesterly. Maximum winds are estimated around 10kt in the northern semi-circle and 25kt in the southern semi-circle. The convective activity is undergoing the influence of a strong vertical wind shear close to 30kt to 40kt from the northeast sector. This constraint, associated with dry air nearby, always prevents the development of this low.

In this context, this circulation should continue to move west-northwestward in the basin towards the Seychelles, while losing its organization. It should disappear at the end of the week, with the presence of dry air in middle troposphere along its path.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

608
AWIO20 FMEE 101045

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/10 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is decreasing over the basin but remains present on the western part near the remains of the circulation monitored for several days and around a large clockwise circulation over the far east of the basin in the Indonesian area.

North of Agalega :

The last observations do not show any more the presence of a closed circulation between Agalega and Mahe. Only a area of low pressure persists in this sector. The convective activity is locally strong in the southern part, where the trade winds are slowing down. Over the following days, convective activity and heavy rains should maintain in the Agalega sector. As for the system, it does not show any potential for intensification.

In the far east of the basin :

For the past 48 hours, an area of low pressure can be identified off the coast of Indonesia between 0 and 5S. The latest observations do not show the presence of a defined circulation within this zone. During the weekend, with the shift of the anticyclonic cell and the strengthening of the upper divergence on the polar side, a circulation could develop while moving within our area of responsibility towards the south-west. Nevertheless, no significant intensification is expected for the moment due to the lac
k of convergence on the northern side and due to the presence of a weak to moderate north-easterly then north-westerly shear.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

585
AWIO20 FMEE 111049

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/11 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is relatively weak on the center of the basin but much more intense on the far Eastern region of the basin, due to the influence of the active MJO phase. A wide clockwise circulation developed East of our AoR border, with a center approximately located near 2.4S/93E. This morning 0130Z ScatSat swath reveals that the North-Eastern semi-circle of this circulation still remains ill-defined.

This weak system should enter our basin over the week-end. Despite a good upper divergence and high mid-level humidities, the strong Easterly to East-North-Easterly upper shear should prevent any significant deepening. Furthermore, a surface trough should pass just South of the low, thus weakening the poleward convergence caused by trade winds. The available guidance is in good agreement on this scenario.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

630
AWIO20 FMEE 130945

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/13 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is relatively weak over the basin except at the eastern edge of the basin, where it is moderate. This activity should continue for another 24 to 48 hours before weakening.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

877
AWIO20 FMEE 141154

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/14 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


A zone of persistent convection is present over the Northeast of the basin between 05oS and 13oS and East of 75oE. While convective activity has shown some signs of organization over the last 24 hours, scatterometric data show that there is no real low levels circulation associated. The low levels inflow is indeed very poor on the equator side especially but also on the trade wind side. The ongoing approach of a deep polar trough from the South-West, will help to completely filling up this weak area of rela
tive low pressure in a day or two.

There is no risk of a moderate tropical storm forming over the next 5 days in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

880
AWIO20 FMEE 161025

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/16 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

892
AWIO20 FMEE 181057

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/18 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

235
AWIO20 FMEE 191030

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/19 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

666
AWIO20 FMEE 201142

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/20 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

326
AWIO20 FMEE 211012

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/21 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

695
AWIO20 FMEE 221047

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/22 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

296
AWIO20 FMEE 230936

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/23 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

328
AWIO20 FMEE 240837

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/24 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

556
AWIO20 FMEE 251115

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/25 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a winter pattern with trade winds crossing the equator into the northern hemisphere.

In the centre of the basin, a low is located near 9.7S/72.5E. According to ASCAT data, the surface circulation appears closed but still elongated with maximum winds of 15 to 20kt. A mesoscale vortex was also discernible this morning in the northwest quadrant away from the convective activity. This system is not expected to intensify due to strong environmental shear in a large-scale dry context.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

782
AWIO20 FMEE 261029

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/26 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

239
AWIO20 FMEE 281011

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/28 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

955
AWIO20 FMEE 291012

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/29 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

840
AWIO20 FMEE 301056

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/09/30 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The south-west Indian Ocean basin is still in a large-scale winter pattern with trade winds up to the equator and in the northern hemisphere, with no equatorial westerly flow.

Over the next few days, under the influence of a Mixed Rossby Gravity Wave, a clockwise circulation could form over the eastern part of the basin. No significant deepening is expected at this time due to a clear lack of surface convergence on the equatorial side and a persistent northeasterly vertical shear.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

258
AWIO20 FMEE 010914

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/01 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin maintains its winter configuration with trade winds that reach up to the equator. Convective activity is moderate in the eastern part of the basin under the effect of a Mixed Rossby Gravity Wave. This convective activity will be maintained or even intensified over the next 5 days as it moves westward in the wake of this wave. Even if a clockwise circulation could form within this zone, no significant deepening is expected for the moment.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

300
AWIO20 FMEE 021140

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/02 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin retains its winter configuration with trade winds that reach up to the equator. However, two areas of deep convection have been in place for a few days in the near equatorial zone: one appeared towards the Seychelles and has shifted eastward today between the Chagos and the Seychelles and the other is located on the extreme North-East of our basin. The filtering of wind anomalies at 850 hPa shows that associated with these thunderstorm areas, there is a signature of Kelvin waves (for the westernmo
st pole) and the Equatorial Rossby wave (for the easternmost pole).

Over the next 2 days, these two equatorial waves will cross over the eastern half of our basin and may participate in the formation of a low-level clockwise circulation even in the absence of a well-defined Near Equatorial Trough (NET) pattern. However, in an environment not really conducive for cyclogenesis (little or no convergence on the equatorial side, persistence of a moderate to strong vertical easterly windshear), there is only a very small risk that this initial disturbance could intensify into a t
ropical storm. There is currently no significant signal on the deterministic models, and the EPS and GEFS ensembles suggest a weak signal between Monday and Wednesday somewhere south of the Chagos Archipelago, whereas this minimum should generally move westward.

For the next 5 days, the risk of formation of a moderate tropical storm becomes very low from Monday over the central part of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

562
AWIO20 FMEE 031153

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/03 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is still showing a winter pattern with trade winds reaching the equator. However, deep convection has been present for a few days in the near equatorial area in the extreme northeastern part of our basin. Related to equatorial waves activity, in particular an Equatorial Rossby wave (analysis based on wind anomalies at 850hPa), a circulation could be form in the eastern part of the basin within a building Near Equatorial Trough.

However, the environment remains globally unfavorable to cyclogenesis: little or no convergence on the equatorial side, persistence of a moderate to strong easterly vertical shear. At long range, these conditions could improve slightly with a decrease of the constraint and a better feeding inflow on the equatorial side. Chances for development of a storm cannot be totally excluded then.

For the next 5 days, the risk of formation of a moderate tropical storm becomes very low on Wednesday over the central part of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

845
AWIO20 FMEE 041047

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/04 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity has increased over the last 24 hours over the northeast part of the basin, north of 10oS and east of 80oE. Ascat data as well as satellite imagery indicate that a weak and poorly defined low pressure circulation may have formed around 3oS and 81oE, associated with weak winds at 10/15 kt and a fairly high minimum pressure of about 1009 hPa.

The current environment around this area, and that expected over the next few days, remains globally unfavorable to cyclogenesis: little or no convergence on the equatorial side, persistence of moderate to strong vertical shear stress from the eastern sector, and we can even add that on Tuesday/Wednesday, dry air of subtropical origin could interfere with this weak circulation via the western semicircle. On Thursday/Friday, these conditions could however slightly and temporarily improve with a decrease in t
he shear constraint and better feeding on the equatorial side. The risk of development of a tropical storm cannot yet be totally excluded, as still suggested by the GEFS and (to a lesser degree) EPS ensemble forecasts.

This system is expected to move in a general westerly direction over the next 5 days.

For the next 5 days, the risk of a moderate tropical storm formation becomes very low from Wednesday onwards over the center of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

270
AWIO20 FMEE 051144

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/05 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity has weakened over the last 24 hours, northeast of the basin. Ascat data as well as satellite imagery show the presence of a broad area of low pressure immediately east of Diego Garcia. The convective activity is mainly present on the southern side of this trough in the trade winds convergence area.

Starting on Wednesday, a small closed surface circulation could form and deepen due to a slightly more favorable environment : appearance of a weak equatorial convergence and temporary decrease of the moderate to strong easterly vertical shear, as shown by GFS 00Z. Though, the deepening of a moderate tropical storm remains unlikely with a possible increase in shear from Thursday as suggested by the IFS 00Z. This system is in any case expected to move westerly over the next 5 days.

For the next 5 days, the risk of formation of a moderate tropical storm remains very low from Wednesday in the center of the basin.

South of the Mascarene Islands, a baroclinic trough should favor the formation of a minimum during the next few hours, moving rapidly southward. On Tuesday, this low could temporarily evolve in conditions favorable to a tropical transition with a significant drop in shear, an excellent upper divergence and sea surface temperatures still above 20oC. In these conditions, although the phasing of the different elements (minimum surface, shear, ...) still seems very uncertain, some runs of the GFS model (18Z,00Z
) propose in their scenario, the building of a system gaining tropical characteristics with gale force winds (8 Beaufort). The different ECMWF models do not suggest such an evolution.

For the next 5 days, the risk of a tropical transition (formation of a subtropical depression) south of the Mascarene Islands is low tomorrow Tuesday and Wednesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

883
AWIO20 FMEE 061029

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/06 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


A broad area of low pressure is present near Diego Garcia. ASCAT swath do not allow the location of a closed low pressure circulation. Convective activity is moderate on the southern side of this area and should persist over the next few days. Within this zone, a closed surface circulation could form during the next 24/48 hours and deepen in a slightly more favorable environment. However, the risk of a moderate tropical storm is not maintained. This system is in any case expected to move in a general wester
ly direction over the next 5 days.

For the next 5 days, there is no risk of a moderate tropical storm forming over the center of the basin.

To the south of the Mascarene Islands, the baroclinic dynamics allow the formation of a minimum low pressure system which is expected to intensify slightly over the next 24 hours. The 0541UTC ASCAT swath allow to estimate winds of about 30kt in the southern part of this system. The environmental characteristics and its southward movement should not allow the system to make a tropical transition. Although the wind values should temporarily reach or even exceed 34kt in the southern sector, this system should
not evolve into a tropical system.

For the next 5 days, there is no more risk of a tropical transition south of the Mascarene Islands.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

652
AWIO20 FMEE 071040

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/07 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


A broad area of low pressure is located at 1000 km west of the island of Diego Garcia. The last ASCAT swaths don't allow to locate a closed low pressure circulation. The convective activity is moderate on the southern side of this area and should continue in the coming days with a loss of intensity. According to the deterministic models, this low is moving towards the Seychelles islands in the coming days. The strongly sheared environment (from East to North-East sector) with dry air intrusions in average t
ropopause will reduce the deepening of this system. The risk of formation of a moderate tropical storm is therefore not conceivable at this stage. This system is in any case expected to move westerly during the next 5 days.

For the next 5 days, there is no risk of a moderate tropical storm forming over the center of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

630
AWIO20 FMEE 081202

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/08 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The weak low pressure area that has been monitored over the last few days is now located about 500 km east-southeast of the main Seychelles islands. The low pressure circulation remains poorly defined with no well-defined center associated with fluctuating convective activity located in the southern semicircle. ASCAT data show weak winds at 10/15 kt and minimum pressure remains high and estimated at 1009 hPa. No significant deepening is still envisaged but this system is expected to drain a more humid air m
ass over the next two days over Southern Seychelles and then over the Northern Mozambique Channel from Sunday onwards.

For the next 5 days, there is no risk of a moderate tropical storm forming over the center of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

059
AWIO20 FMEE 091137

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/09 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The weak low followed for the last few days, is located today east of the island of Coetivy. The circulation of low layers remains poorly defined with no well-defined center with no convective activity noted today. ASCAT swaths from 05h15UTC show weak winds of about 15 kt near the maximum in the southern part of the area and the minimum pressure remains high compared to yesterday and is estimated at 1012 hPa. No significant deepening is still envisaged but this system will drain a more humid air mass over t
he next two days over the Southern Seychelles and then over the Northern Mozambique Channel from Sunday.

For the next 5 days, there is no risk of a moderate tropical storm forming over the center of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

204
AWIO20 FMEE 100953

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/10 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

646
AWIO20 FMEE 111139

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/11 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is weak to moderate over the easternmost part of the basin. In relation with an increasing wave activity, especially the arrival of a new equatorial Rossby wave, a low level circulation may form east of the basin, in the following days. Despite a good lower feeding from the southern side, the equatorial low level flow will remain zonal and poorly convergent limiting the chances for cyclogenesis. Furthermore, the deep wind shear is also expected to hinder the system.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

850
AWIO20 FMEE 120810

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/12 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is weak to moderate over the easternmost part of the basin. In relation with an increasing wave activity, especially the arrival of a new equatorial Rossby wave, a low level circulation may form east of the basin, in the following days. Despite a good lower feeding from the southern side, the equatorial low level flow will remain zonal and poorly convergent limiting the chances for cyclogenesis. Furthermore, the deep wind shear is also expected to hinder the system.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

840
AWIO20 FMEE 130958

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/13 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is moderate to strong over the easternmost part of the basin. The ASCAT swath of 0309UTC show a wide and weak closed circulation in the extreme east of the basin around 5oS/89oE. In connection with the passage of an equatorial Rossby wave, this circulation is expected to continue or even intensify slightly during the week as it shifts westward. Despite the good surface convergence on the south side, on the north side the flow will essentially keep a zonal westerly component with little c
onvergence limiting the risk of development. Conditions therefore remain unfavorable to cyclogenesis.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

616
AWIO20 FMEE 141045

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/14 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is moderate to strong on the extreme east of the basin within the building near equatorial trough. Scatsat data from 0315Z suggest the possible presence of a closed clockwise circulation within the broad low level trough. However, it remains difficult to clearly discern this structure on the latest satellite images and the few available microwave images. It could be located at 10Z around 5.5S 85.5E.

In relation with the passage of an equatorial Rossby wave, this circulation should persist or even slightly intensify while moving southwestward, drawn towards a flat low circulating at south. On this track, the system should indeed benefit from an increase in upper divergence and a significant decrease in shear under the equatorial ridge. Nevertheless, the moderate tropical storm threshold is not expected to be reached. The convergence on the equatorial side will remain very weak, especially from Friday, w
hen the circulation will be too far from the equatorial westerly. The deep shear is also expected to increase significantly from this weekend onwards as the upper trough in the southwest quadrant approaches. This scenario is well in agreement with the main deterministics. Only a few members of the ensemble forecast propose winds close to gale force winds, but their number does not appear significant at the moment.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

700
AWIO20 FMEE 151053

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/15 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is moderate to strong on the extreme east of the basin, mainly east to 70E, within the building near equatorial trough. Satellite animation seems to confirm the possible presence of a closed clockwise circulation within the broad low level trough. However, it remains difficult to clearly discern this structure on the latest satellite images and the few available microwave images. It could be located at 10Z around 5.5S 80.5E.

In relation with the passage of an equatorial Rossby wave, this circulation should persist or even slightly intensify while moving southwestward, drawn towards a flat low circulating at south. On this track, the system should indeed benefit from an increase in upper divergence and a significant decrease in shear under the equatorial ridge. Nevertheless, environmental conditions do not permit this low to reach the moderate tropical storm stage. The convergence on the equatorial side will remain very weak, e
specially from Friday, when the circulation will be too far from the equatorial westerly. The deep shear is also expected to increase significantly from this weekend onwards as the upper trough in the southwest quadrant approaches. This scenario is well in agreement with the main deterministics.A few more Members than yesterday of the ensemble forecast propose winds close to gale force winds, but their number does not yet appear significant at the moment.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

500
AWIO20 FMEE 181046

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/18 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity is moderate in the center of the basin, on the south side of the near equatorial trough.The satellite animation allows to detect a vortex completely exposed to the North-East of the convection due to a strong vertical wind shear of the order of 30kt according to the CIMMS data, around 11.4S/67.2E around 09utc. ASCAT-A swath of 0330UTC show a fairly wide closed circulation localized around 11.4S/67.2E with winds reaching 20kt in the southern semicircle. Due to a gradient effect with the
anticyclonic cell circulating in the South, this circulation should temporarily present winds close to 25/30kt over a limited portion of its southern part during the next 24h. Thereafter, the persistence of the northern vertical windshear should stopp the potential intensification of this circulation. The risk is maintained at a low level.

For the next 5 days, the likelihood of the development of a moderate tropical storm, south of Diego-Garcia, is low today and Monday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

262
AWIO20 FMEE 201009

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/20 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in the configuration of Near Equatorial Trough (NET). The convective activity is moderate, mainly in the area of slowing trade winds on the south side of the NET. This convective activity should continue for the next 48 hours.

The minimum monitored for several days is now only detectable in the form of a large clockwise circulation near the Seychelles archipelago. The 0548UTC ASCAT swath show winds reaching 25kt with difficulty in the southern part of the circulation.

For the next 5 days, there is no likelihood for the development of a moderate tropical storm.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

480
AWIO20 FMEE 231133

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/23 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is weak to moderate close to the Near Equatorial Trough pattern over the basin. During the next few weeks, the arrival of a dry MJO phase is expected to limit the presence of westerly flow at the equator favouring a poorly conducive pattern for the formation of a tropical storm. From mid-November onwards, the situation could become then more favorable to cyclogenesis with the possible return of a wet MJO phase.



Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

930
AWIO20 FMEE 241017

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/24 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity remains globally weak in the vicinity of the near equatorial trough in place over the northeastern basin.

During the next two weeks, a dry MJO pulse should limit the equatorial westerlies favoring a poorly conducive pattern to the formation of a tropical storm. From mid-November onwards, the situation could become then more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

269
AWIO20 FMEE 251118

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/25 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a Near Equatorial Thalweg (NET) configuration in place over the northeastern basin, with no major associated convective activity.

Over the next two weeks, the drift of a dry pulse of the MJO should limit the presence of the westerly flow at the equator, favoring a poorly conducive pattern to the formation of a tropical storm. From mid-november, the situation should become more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

187
AWIO20 FMEE 260851

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/26 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Over the next two weeks, the drift of a dry pulse of the MJO should limit the presence of the westerly flow at the equator, favoring a poorly conducive pattern to the formation of a tropical storm. From mid-november, the situation should become more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

422
AWIO20 FMEE 271114

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/27 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


No significant convective activity over the basin.

Over the next two weeks, the drift of a dry pulse of the MJO should limit the presence of the westerly flow at the equator, favoring a poorly conducive pattern to the formation of a tropical storm. From mid-november, the situation should become more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

420
AWIO20 FMEE 280952

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/28 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity in our basin is poor to moderate, mainly in the eastern edge of the basin.

Over the next 10 days, the drift of a dry pulse of the MJO should limit the presence of the westerly flow at the equator, favoring a poorly conducive pattern to the formation of a tropical storm. From mid-november, the situation should become more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

159
AWIO20 FMEE 291032

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/29 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Near Equatorial Thalweg (NET) configuration on the northeast quarter of the basin. The convective activity associated is weak to moderate. There is no well-organized circulation in the basin at present.

Over the next 10 days, the drift of a dry pulse of the MJO should limit the presence of the westerly flow at the equator, favoring a poorly conducive pattern to the formation of a tropical storm. From mid-november, the situation should become more favorable for cyclogenesis with the possible return of a wet pulse of the MJO.

Development of a moderate tropical storm is not expected for the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

587
AWIO20 FMEE 311122

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/10/31 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a Near Equatorial Trough (NET) pattern on the northeast quarter of the basin associated with low to moderate convective activity with no suspicious areas.

At 12hUTC, presence of a low pressure system centered south-southeast of Rodrigues Island at 24o45 S / 64o20 E, associated with strong gale force winds according to the last swath this early morning. This low should then slowly drift towards the South-South-East and weaken during the following days.

For the next 5 days, there is no risk of a moderate tropical storm forming.

Next week, the dry phase of the MJO continues to limit the presence of the westerly flow at the equator favoring a configuration unfavorable to the formation of a tropical storm.

From the week of November 9 and for the next two to three weeks, the situation should again become more favorable for cyclogenesis with the implementation of a wet phase of the MJO associated with a strengthening of equatorial westerly winds accentuating the cyclonism of low layers within the NET configuration or even double NETs (one in each hemisphere) in the central and eastern part of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

090
AWIO20 FMEE 011152

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/01 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a weak configuration of Near Equatorial Trough (NET), associated with a weak to moderate convective activity.

Low south-south-east of Rodrigues :

Since yesterday morning, a minimum developped within a baroclinic area (interaction between the upper cold anomaly and the warm surface one). By moving under the high altitude trough, the system gained characteristics of tropical systems, including a symmetrical surface warm core. Nevertheless, since this initial extratropical deepening phase, the system has been unable to complete its tropical transition and did not deepen anymore due to the lack of sustained convective activity close to the centre. The we
sterly mid level shear rapidly strengthened, bringing dry air over the inner core. This can be clearly seen today with the presence of a symmetrical vortex towards 25.1S/65.9E at 10Z without any deep convection. Maximum winds reached 35/40kt last night according to ASCAT passes. This morning the Scatsat data from 0254Z still show the presence of near gale force wind (30kt). The low is filling up and should disappear by tomorrow evening.

For the next 5 days, there is no risk of a moderate tropical storm forming.

Next week, the dry phase of the MJO is expected to progressively limit the presence of the westerly flow at the equator favoring a pattern poorly conducive for the formation of a tropical storm.

From the week of November 9 and for the next two to three weeks, the situation should again become more favorable for cyclogenesis with the arrival of the wet phase of the MJO associated with strengthening equatorial westerly winds improving the vorticity of low layers thanks to a NET pattern or even a double NETs (one in each hemisphere) in the central and eastern part of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

334
AWIO20 FMEE 021146

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/02 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a weak Near Equatorial Trough (NET) pattern, associated with a convective activity that has become weak over the last 24 hours.

For the next 5 days, there is no risk of a moderate tropical storm forming.

This week, the dry phasis of the MJO limits the presence of the westerly flow at the equator favoring a configuration unfavorable to the formation of a tropical storm.

From the week of 9 November and for the next two to three weeks, the situation should become more favorable for cyclogenesis with the implementation of a wet phase of the MJO associated with a strengthening of equatorial westerly winds enhancing low level vorticity within the NET pattern or even double NET (one in each hemisphere) over the central and eastern part of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

200
AWIO20 FMEE 031012

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/03 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a weak Near Equatorial Trough (NET) pattern, associated with a weak convective activity over the last 48 hours.

For the next 5 days, there is no risk of a moderate tropical storm forming.

This week, the dry phasis of the MJO limits the presence of the westerly flow at the equator favoring a configuration unfavorable to the formation of a tropical storm.

From the week of 9 November and for the next two to three weeks, the situation should become more favorable for cyclogenesis with the implementation of a wet phase of the MJO associated with a strengthening of equatorial westerly winds enhancing low level vorticity within the NET pattern or even double NET (one in each hemisphere) over the central and eastern part of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

331
AWIO20 FMEE 051049

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/05 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The eastern half of the basin is in a near equatorial trough (NET) pattern. Deep convection has triggered and strengthened East of 80E overnight. This morning available observation data do not confirm the presence of a closed surface circulation while CIMSS analysis only shows a weak low-level vorticity core over the area. Within unconducive environmental conditions over the next days, no significant development is forecasted in this area.

Early next week, as the NET pattern spreads over the central part of the basin thanks to the weakening influence of the dry MJO phase, a weak clockwise circulation should enter our AoR from the East. Some tropical waves filtering data suggest that it could be related to the propagation of an Equatorial Rossby wave. At first, this weak system could encounter neutral to rather conducive conditions. However, no significant deepening is awaited before the end of the forecast period on Tuesday. Later, the ensemb
le guidance suggest a still uncertain and rather low risk of cyclogenesis.

For the next 5 days, there is no risk of formation of a moderate tropical storm over the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

563
AWIO20 FMEE 061039

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/06 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The eastern half of the basin east of 70oE remains in a near equatorial trough (NET) pattern, axed along 4-5oS, without the presence of any suspicious area and without any notable increase in associated thunderstorms activity over the last 24 hours.

On the other hand, more to the west, the deep convection has increased in an area of relative low pressure located to the east of the Seychelles archipelagos between the equator and 8oS and between 55oE and 65oE. Ascat data, satellite images and surface observations do not allow to isolate a well-defined surface circulation, although the low levels flows show a cyclonic trend, confirmed by the 850 hPa vorticity analysis of the CIMSS.

Environmental conditions appear favorable for the cyclogenesis process at present. The convergence at the low levels is good between the trade winds to the South and a small trans-equatorial flow that has managed to set up in the area. The oceanic potential is good, the shear is low and the upper-levels divergence is good especially on the South side where it is in phase with a jet entry. However, these good environmental conditions are not expected to continue with a fairly clear drop in the low levels co
nvergence in about 24 hours, linked to the disappearance of the trans-equatorial flow. None of the main global models proposes a significant deepening of this system. The latest available ensemble forecasts from the European center and (to a lesser degree) from the GEFS, suggest a very small possibility of deepening. Given the expected evolution of the environment, no risk of cyclogenesis is currently associated with this zone. It should drift slowly in a general west-sout
hwest di
rection over the next few days, giving a temporarily disturbed weather on the main islands of the Seychelles tomorrow.

At the end of the period, a weak low pressure circulation could arrive on the basin from the East. Some equatorial waves filtering techniques associate it with the propagation of an Equatorial Rossby wave. On Wednesday / Thursday, a crossing with a Kelvin wave, associated with a strengthening of equatorial westerly winds, could give more favorable conditions for cyclogenesis. The risk of cyclogenesis is very low over the period (until Wednesday) but increases over the second part of next week.

For the next 5 days, the risk of a tropical storm formation becomes very low from Wednesday over the North-Eastern part of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

856
AWIO20 FMEE 071232

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/07 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The eastern part of the basin east of 70oE remains in a Near Equatorial Trough (NET) pattern, along 4-5oS, without the presence of any suspect area. Further west, the convective activity became less organised near the Seychelles from the equator to 8oS.

Near the Seychelles :

Between 40 and 55E, the latest observations (Scatsat, Ascat, satellite images, microwaves...) show the presence of a very wide surface trough along 5S with the possible presence of a more compact circulation near 50E (Scatsat 0428Z). However, convective activity remains mainly driven by the convergence of the trade wind flow and is still fairly weak in the northern semi-circle. In the wake of this trough, there are two other non-closed surface circulations (one around 10S/65E and the other near 13S/73E).

This group of low pressure systems is not related to any risk of cyclogenesis for the next few days. Indeed, this zone benefited from a good feeding on its southern side with the presence of a converging trade wind and the temporary presence of a small monsoon flow for the one west of the Seychelles on the northern side. Nevertheless, conditions will deteriorate in the coming hours with the disappearance of the transequatorial flow and the persistence of a weak easterly shear. The size of this broad surface
trough is undoubtedly also a factor that is unfavourable to its development. Still, the latest numerical models suggest that by the beginning of next week, a very small vortex may isolate from the trough and possibly slightly intensify while moving towards Tanzania. This scenario is still very unlikely at the moment.

For the next 5 days, there is no risk of a moderate tropical storm forming over the western part of the basin.

At the extreme east of the basin :

In the middle of next week, under the impulse of several tropical waves (notably Equatorial Rossby) in a large-scale context increasingly favourable for cyclogenesis (arrival of the active phase of the MJO), a weak low-pressure circulation could enter the near equatorial trough in our basin and begin a deepening phase. The environmental context looks particularly favourable from Thursday and onwards, with the strengthening of the trade winds in the southern semi-circle and the appearance of a transequatoria
l flow in the north-eastern quadrant. The conditions at upper levels also look fairly favourable with the presence of a ridge fairly north near 7S with a very good divergence. A longer term, the deepening of the low seems rather likely.

For the next 5 days, the risk of a tropical storm formation becomes very low from Thursday on in the North-East of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

277
AWIO20 FMEE 081029

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/08 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The eastern part of the basin east of 70oE remains in a near-equatorial trough (TPE) pattern, along 4-5oS, without the presence of a suspicious zone. Further west, and since yesterday, convective activity became less organised near the Seychelles between the equator and 10oS.

Near the Seychelles :

Between 43 and 65E, the latest observations (Scatsat, Ascat, satellite images) show the presence of a huge wide surface trough around 7S. The convective activity is driven by the convergence of the trade winds flow and remains rather weak in the northern semicircle. In the extension of this trough, another non-closed surface circulation is present around 12S/70E.

This area of low pressure is not related to any risk of cyclogenesis over the period. Indeed, this area benefited from a good feeding on its southern side with the presence of a converging trade wind flow and the temporary presence of a small monsoon flow in the west on the northeast of the Seychelles. therefore, conditions will deteriorate in the coming hours with the disappearance of the transequatorial flow. The size of this broad surface trough is undoubtedly an element also unfavourable to its intensif
ication.

For the next 5 days, there is no risk of a moderate tropical storm forming over the western part of the basin.

At the extreme east of the basin :

In the middle of next week, under the impulse of several tropical waves (in particular Equatorial Rossby's wave) in a large-scale context increasingly favourable for cyclogenesis (arrival of the active phase of the MJO), a weak low pressure circulation could enter the near equatorial trough in our basin and begin a deepening phase. The environmental context looks particularly favourable from Thursday onwards with the strengthening of the trade winds in the southern semi-circle and the appearance of a transe
quatorial flow in the north-eastern quadrant.

Conditions at upper levels also look fairly favourable with the presence of a ridge fairly north near 7S with a very good divergence. A longer term, the deeping of this low rather likely.

For the next 5 days, the risk of a tropical storm formation becomes very low from Thursday on in the North-East of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

641
AWIO20 FMEE 091039

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/09 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Convective activity remains strong along the near equatorial trough (NET), which lies East of 55E on our basin. East of 90E, a wide clockwise circulation without any well defined center is brewing near the border of our area of responsability.

Near the Seychelles :

A large convection area is still present in the East of the main Seychelles archipelago, in the bottom of the NET and on its equatorial side, where surface convergence is the strongest. In this area, strong upper divergence also strengthens deep convection. No well-defined surface circulation is present in this zone, scatt data from this morning confirm this despite the presence of a few cores of low vorticity, including one near Diego Garcia.

Over the next few days, only some deterministic GFS runs and some GEFS and EPS ensemble members suggest the formation of a closed clockwise circulation, with a very low probability of reaching the moderate tropical storm stage by Saturday.

For the next 5 days, the risk of formation of a moderate tropical storm becomes very low over the western part of the basin.

East of 80E :

Under the impulse of a strong wave activity ahead of a positive MJO currently approaching the African continent, a favourable context for cyclogenesis is being set up on the East of the basin. In particular, the arrival of an Equatorial Rossby wave should allow the entry of a still weak but closed clockwise circulation on the East of the basin by the middle of the week.

From Thursday onwards, this weak system should find rather conducive environmental conditions for its development: a good poleward low-level convergence, high mid-level humidities and low wind shear. Indeed, the westward shift of the surface circulation centre should compensate for the presence of a slight eastward constraint aloft.

Consequently, the available deterministic and ensemble guidance give more and more credit to a cyclogenesis scenario over the next weekend.

From Saturday, the risk of a tropical storm formation becomes moderate South of the Chagos archipelago.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

833
AWIO20 FMEE 101057

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/10 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a near equatorial trough (NET) configuration. The convective activity is moderate to strong, mainly on the north side of this NET east of 60oE. Within this NET, two wide clockwise circulation area can be detected, as specified below.

Near the Seychelles :

No surface circulation is really well established in this large clockwise circulation area as shown by 0510UTC ASCAT swath. Over the next few days and following the last runs of the ensemble models, a circulation could become a little more established, competing with the circulation developing further east, at the eastern end of the basin.

For the moment, the scenario for the development of this circulation is not privileged and the risk of the formation of a moderate tropical storm associated with this zone remains very low.

For the next 5 days, the risk of formation of a moderate tropical storm is very low over the western part of the basin, from Saturday onwards.

East of 80E :

Under the impulse of a strong wave activity ahead of a positive MJO currently approaching the African continent, a favourable context for cyclogenesis is present set up on the East of the basin. The 0329UTC ASCAT swath show a still wide but closed clockwise circulation around 3oS/95oE. In this favorable context, the different models reinforce this circulation during the next few days, which is contrary to the more westerly circulation described in the paragraph above.

In this perspective of preferring this circulation at the eastern end of the basin, this weak system should find environmental conditions rather favorable for its development and thus present a moderate risk of formation of a moderate tropical storm within 3 to 4 days.

Examination of the next runs will make it possible to favor one or the other of the two circulations.

The risk of formation of a moderate tropical storm is moderate from Friday between the Chagos Archipelago and the East of the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

400
AWIO20 FMEE 111242

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/11 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a Near Equatorial Trough (NET) pattern on the northeast of the basin and centered around 5oS. Convective activity is moderate and is mainly located around the NET. There is a strong convective activity on the northeastern edge of our domain around 3oS-91oE, in connection with the suspect area monitored since a few days, and two large low-pressure zones can be detected, as detailed below:

South of the Chagos:

The last ASCAT-B data of 0451UTC and the ScatSat-1 data of 0230UTC show a wide open trough towards 9oS/72oE. Observed winds are weak within its core; the strongest winds, close to 15/20 kt are far from the center. The latest satellite images do not show a significant evolution since this morning. A weak zone of vorticity is still observed, without much associated convection near the island of Diego Garcia.

During the next few days, this zone of vorticity could persist or even strengthen thanks to the presence of good trade winds. Nevertheless, from Saturday onwards, the northerly shear will strengthen while, at the same time, the convergence on the polar side is likely to be disrupted by the formation of the system on the eastern side of the basin. The risk of a storm genesis therefore appears to be rather limited. The last deterministic runs do not show any associated gale force winds.

For the next 5 days, the risk of formation of a moderate tropical storm over the western part of the basin is very low on Saturday and Sunday.

At the extreme northeast of the basin:

The ASCAT-A of 0130UTC shows a large closed circulation around 3oS/92oE (in the Indonesian AoR), without a well defined center. Observed winds are weak within its core and reach 20kt in the southern and eastern semicircle.

According to the latest satellite images, the convective activity seems to be shifted eastward with respect to the center of the circulation.

The suspected zone evolves towards the southwest, in good environmental conditions (no shear, no dry air intrusion in upper levels, with a good divergence, and warm waters).

The tropical storm intensity will probably be reached in the next few days. There is still some uncertainty about the timing of the intensification (GFS being faster than IFS).

The risk of tropical storm formation is moderate on Thursday and becomes Important on Friday east of the Chagos Archipelago.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

048
AWIO20 FMEE 121232

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/12 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil but warnings WTIO20 and WTIO30 to be issued on Tropical Disturbance 01-20202021

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a Near Equatorial Trough (NET) pattern on the northeast of the basin and centered around 5oS. Convective activity is moderate to strong especially around Tropical Disturbance 01.

Near the Chagos:

A second large area of intense convection is located over the central part of the basin, between 55E and 75E, within the NET pattern. In particular, the analysis of sat vis imagery reveals a low/mid level vorticity core located in the South-Western vicinity of the Chagos archipelago. This is also seen on CIMSS analysis data. However, this morning 0330Z ASCAT-A and ScatSat-1 scatt swath did not show any closed surface circulation in the area, only a strong convergence between trade winds and a North-Westerly
flow descending from the equator.

As soon as tomorrow, available guidance show the appearance of a closed surface circulation originating from the aforementionned vorticity core. The upper divergence and good low-level conditions should allow the weak system to gain definition at first. However, from Sunday afternoon, a moderate North-Easterly shear, associated with mid-level dry air from Monday, should hinder further development. Thus, it is still unclear if the system will have the time to reach the tropical storm stage before the arrival
of less conducive upper conditions. The cyclogenesis signal has increased and is now moderate in the last ensemble guidance runs available.

The risk of formation of a moderate tropical storm in the South-West of the Chagos archipelago becomes moderate from Saturday.

Tropical Disturbance 01-20202021 :

Warnings WTIO20 and WTIO30 to be issued shortly.

Position at 10Z: 4.5S/88.0E

Maximum winds : 25kt

Central MSLP : 1002hPa

Movement : Westerwards 2kt

The risk of tropical storm formation is becoming very important from tonight and onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

430
AWIO20 FMEE 131104

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/13 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil but warnings WTIO20 and WTIO30 to be issued on Tropical Disturbance 01-20202021

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin remains in a Near Equatorial Trough (NET) pattern centered between 05S and 10S east of 60oE. The associated convective activity is focused around two areas of low pressure: system no01 and a still suspicious area located to the southwest of the Chagos archipelago.

Southwest of the Chagos:

During the last 24 hours, this area has not seen any clear improvement in its organization. The Ascat data do not allow to identify a well defined surface circulation. The convective activity is locally strong but shows no real signs of organization.

Over the next two days the strengthening of the equatorial westerly winds will induce a strengthening of the low levels vorticity within this suspect area. Thus, a much better defined circulation should potentially appear as early as tomorrow. On the other hand, the system should slowly evolve along the northern edge of the upper levels ridge and experience a persistent east-to-northeasterly constraint that could be associated with mid-levels dry air intrusion at the beginning of next week. The latest numer
ical guidance do not show an increasing risk of cyclogenesis for this area.

The risk of tropical storm formation South-West of the Chagos archipelago remains moderate between Saturday and Monday.

Tropical Depression no01-20202021 :

Position around 09Z : 5.9S / 83.2E
Maximum wind : 30kt
Central pressure: 999 hPa
Current movement: Southwestwards at 11kt

The risk of a tropical storm formation becomes very important from this night on the east of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

709
AWIO20 FMEE 141121

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/14 AT 1200 UTC

PART 1:

WARNING SUMMARY:

Bulletins WTIO20 FMEE no008/1 et WTIO30 FMEE no8/1/20202021 on Severe Tropical Storm ALICIA issued at 06Z. Next warnings at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The thunderstorm activity is strong over the central Indian Ocean in connection with Severe Tropical Storm ALICIA and an area of disturbed weather monitored since several days between the Seychelles and the Chagos archipelago.

Disturbed weather zone southwest of the Chagos archipelago:

The suspect zone, which has been monitored for several days southwest of the Chagos Islands, has shown no signs of intensification in the last 24 hours. However, the Ascat pass of 0529Z shows that a closed circulation is isolating itself near 8.3oS and 65.1oE on the western edge of a low-levels trough axed along 7-8oS between 64oE and 71oE. Maximum winds are estimated at 20/25 kt and central pressure at 1005 hPa. Associated convective activity is locally strong but present only in the southwest quadrant due
to a strong easterly shear generated by ALICIA's outflow.

The environmental conditions appear marginally favorable for an intensification to tropical storm stage: Equatorial westerly winds continue to induce a strengthening of the vorticity of low layers but on the other hand, the system evolves along the northern edge of the upper levels ridge and is exposed to a persistent Easterly to Eastnortheasterly shear accompanied by dry air intrusion in the mid-levels.

The system is expected to drift generally eastwards until Monday and then curve southeastwards in the wake of ALICIA.

The risk of a tropical storm forming in the southwest and then south of the Chagos becomes low until Monday.

Severe Tropical Storm ALICIA :

Position at 09Z: 9.3S / 77.9E
Maximum Wind: 50 kt
Central pressure: 992 hPa
Current movement : South-Westwards at 13 kt

For further information, please refer to bulletins WTIO20 and WTIO30 FMEE issued at 06Z and followings.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

411
AWIO20 FMEE 150952

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/15 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no012/1 et WTIO30 FMEE no12/1/20202021 on Severe Tropical Storm ALICIA issued at 06UTC. Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The convective activity is strong in the central part of the Indian Ocean in connection with Severe Tropical Storm ALICIA and the tropical disturbance monitored since several days between the Seychelles and the Chagos archipelago.

Tropical Disturbance southwest of the Chagos archipelago:

The convective activity associated with the suspect zone, which has been monitored for several days in the southwestern Chagos, has consolidated over the last 24 hours. Due to the shear generated by ALICIA in this area, convection is present only in the western part of the tropical disturbance. The partial ASCAT swath of 0509UTC shows winds of about 30kt in the northern part of the circulation, for a circulation center estimated around 9.2S/67E. This circulation is affected by the presence of ALICIA to the
southeast of the system, preventing a consolidation of the circulation. The sheared environment generated by the presence of ALICIA thus limits the potential for intensification of this tropical disturbance and although winds could reach 34kt very locally in the northern part, this system should not be able to intensify significantly during the next 24 hours.

The system is expected to drift generally eastwards until Monday and then curve southeastwards in the wake of ALICIA.

The risk of a tropical storm forming in the southwest and then south of the Chagos becomes low until Monday.

Severe Tropical Storm ALICIA :

Position at 09UTC: 13.2S / 73.8E
Maximum Wind: 55 kt
Central pressure: 985 hPa
Current movement : South-Westwards at 14 kt

For further information, please refer to bulletins WTIO20 and WTIO30 FMEE issued at 06UTC and followings.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

807
AWIO20 FMEE 161026

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/16 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no016/1 et WTIO30 FMEE no16/1/20202021 on Tropical Cyclone ALICIA issued at 06UTC.

Bulletins WTIO20 FMEE no03/2 et WTIO30 FMEE no3/2/20202021 on Tropical Depression 02-20202021 issued at 06UTC.

Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is weak to moderate over the Indian Ocean and is mainly concentrated near the two tropical lows currently monitored.

Tropical Depression 02-20202021 :

Position at 0830UTC: 9.2S / 72.0E
Maximum Wind: 30kt
Central pressure: 999 hPa
Current movement : Eastward at 20 kt

The risk of a tropical storm forming south of the Chagos is very low until Wednesday.

Severe Tropical Storm ALICIA :

Position at 0830UTC: 16.1S / 72.2E
Maximum Wind: 60 kt
Central pressure: 980 hPa
Current movement : South-Westwards at 6 kt

For further information, please refer to bulletins WTIO20 and WTIO30 FMEE issued at 06UTC and followings.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

691
AWIO20 FMEE 171209

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/17 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no016/1 et WTIO30 FMEE no16/1/20202021 on filling up ALICIA issued at 06UTC.

Last warning of this system.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The convective activity is concentrated nearby the two active systems, monitored on the basin.

These two systems are currently filling up.

Filling up depression 02-20202021:
Position near 0230UTC (fix SacatSat 1): 12.2S / 74.3E.
Maximum wind: 20 kt.
Moving: SE 10 kt.

This weak system encounters detrimental high environmental constraints.

The available guidance make this system disappear by Thursday.

The risk of formation of a tropical storm is now averted.

Filling up depression ALICIA:

Position near 0900UTC: 17.1S / 73.3E.
Maximum wind: 30 kt.
Central pressure: 996 hPa.
Moving: SSE 3 kt.

For further information, please refer to WTIO20 and WTIO30 FMEE warnings issued at 06UTC.

00UTC GFS model run and some of its ensemble members suggest the emergence of a low nearby Chagos Archipelago this week-end. Nevertheless, due to unconducive environmental conditions forecasted over the north of the basin, no significant development is expected.

There is no risk of tropical storm development.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

684
AWIO20 FMEE 181118

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/18 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Over the basin, deep convection is mainly located within the convergence East of the filling up low ALICIA, which keeps on drifting South-Westard. Over the Eastern region of the basin, convection is also strong within the near equatorial area due to an important tropical wave activity (positive MJO phase and an associated Kelvin wave propagating ahead).

Filling up depression ALICIA:

Position near 0900UTC: 19.6S / 69.6E
Maximum wind: 30 kt, within the South-Eastern quadrant and far from the center due to pressure gradient
Motion : SouthWestward at 7 kt.

ALICIA became a low-level vortex, which should evacuate towards the mid latitudes by next week-end, with a surface trough circulating in the South. Environmental conditions forbid any re-intensification.

There is no risk of ALICIA re-intensifying into a tropical storm.

Near the Chagos archipelago from Friday :

With a significant Equatorial ROssby wave propagating Westward, a clockwise circulation could develop near Diago Garcia by this week-end. However, while the last GFS model runs suggest the emergence of a a relatively well-defined closed circulation, the european model IFS does not share this scenario. IFS does not forecast enough low-level convergence equatorward to allow for the constitution of a real vorticity core.

At first, environmental conditions would be unconducive for a possible developing tropical system. However, they could improve over the week-end with a weakening shear constraint and a strong upper divergence boosted by a deep trough axed over the Mascarenes area. As of now, only a rare few members of the available ensemble models suggest a cyclogenesis risk for the beginning of next week.

The risk of formation of a moderate tropical storm South-West of the Chagos becomes very low from next Monday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

848
AWIO20 FMEE 191127

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/19 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Since the last 24 hours, deep convection has strengthened in the north of the Seychelles archipelago and east of the Chagos archipelago.

The convective activity is to be linked with the important wave activity currently underway in the north of the basin (active phase of MJO, as well as the Kelvin wave, and an equatorial Rossby wave in the north of the Seychelles).

Filling up depression ALICIA :
Position about 0900UTC: 21.0S / 66.1E.
Maximum wind: 25 kt (based on ASCAT-A of 0430UTC), within the South and Southwest quadrant, pretty far from the center by pressure gradient effect. Motion: West-South-West at 9 kt.

There is only a low level vortex from ALICIA, which is expected to evacuate towards mid-latitudes by next weekend, thanks to the transit of a surface trough, in the south of the Mascareignes. Environmental conditions still forbid any re-intensification.

There is no risk that ALICIA will again become a moderate tropical storm in the coming days.

Near the Chagos Archipelago from Friday:

With a significant westward propagation of a powerful Equatorial Rossby wave, a clockwise circulation could develop near Diego Garcia by this weekend. However, while the last GFS model runs suggest the emergence of a relatively well defined closed circulation, the European model IFS and EPS don't share this point of view. Indeed, IFS model does not forecast enough low level convergence equatorward for the constitution of a real vorticity core. Also, the ensemble members pressure center of the american ensem
ble model (GEFS), show scattered points of high pressure only.

There is no risk of a tropical storm forming over the next five days in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

130
AWIO20 FMEE 201155

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/20 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is still strong over the eastern part of the basin in connection with important equatorial wave activity (MJO, Equatorial Rossby, ...). However, the near equatorial trough remains poorly organised with weak westerlies, which may be linked to the arrival of a negative upper divergence anomaly due to the dry phase of the MJO. In this context, the data from the latest monthly forecasts do not indicate any particular risk of cyclogenesis for the next two weeks.

A small vortex with no potential is present to the north-east of Agalega.

Filling up depression ALICIA :

Position at 0900UTC: 24.1S / 66.1E.

Maximum wind: 20 kt (based on ASCAT of 0509UTC), in the South and East semi-circle, away from the centre by gradient effect.

Motion: South-East 14 kt.

All that remains of ALICIA is a vortex of low layers that is expected to evacuate towards mid-latitudes by tomorrow, absorbed by the surface thalweg that circulates at south.

ALICIA is not expected to become a moderate tropical storm again in the coming days.

In the vicinity of the Chagos Archipelago :

The latest observations do not indicate a closed circulation, however there was little scatterometric data this morning in this area (10S/78E). Over the next few days, the environmental conditions do not look very favourable, with almost no equatorial feeding and the presence of a weak easterly then westerly shear. This minimum could therefore persist for a few more days in the basin before disappearing.

Development of a moderate tropical storm over the basin is not expected during the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

246
AWIO20 FMEE 211115

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/21 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is low to moderate over the northeast quarter of the basin.

The Near Equatorial Trough (NET) is quite noisy due to the presence of two low pressure areas: one located west of Agalega, which remains without potential at this time, and another one located south-southeast of Diego Garcia.

The NET presents a poor organization, due to weak equatorial westerly winds.

In this context, the data from the latest monthly forecasts do not indicate any particular risk of cyclogenesis for the next five days.

Filling up depression ALICIA :

Position at 0900UTC: 32.1S / 75.5E.

Maximum wind: 30 kt (based on ASCAT-B of 0430UTC), in the northern quadrant, away from the center by gradient effect.

Motion: Southeast 30 kt.

Only one low level vortex remains from ALICIA, which is expected to evacuate towards mid-latitudes by Sunday, absorbed by the surface trough circulating in the south.

ALICIA is not expected to become a moderate tropical storm again in the coming days.

In the vicinity of Diego Garcia :

The ASCAT-B swath of 0430UTC does not present a well organized clockwise circulation (maximum winds around 20 kt in its southern part). In analysis, this low pressure area undergoes on its northern part, a strong altitude wind shear of northeastern sector. In low layers, the convergence is not very marked. During the next few days, the environmental conditions looks unconducive with a weak equatorial feeding and the presence of a strong northwestern wind shear at the end of the period and to finish an intru
sion of dry air at high altitude.

This minimum could therefore persist for a few more days on the basin before disappearing completely.

Deterministic and ensemble models agree on this scenario.

Development of a moderate tropical storm over the basin is not expected during the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

577
AWIO20 FMEE 221053

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/22 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Within the near equatorial area, the large-scale atmospheric circulation is disturbed by tropical wave activity : a mixed Rossby-Gravity and an Equatorial Rossby wave are detected by available dedicated filters. Thus, the near equatorial trough pattern that seems to emerge over the basin is still quite ill-defined at the moment but should improve over the next few days. Two weak clockwise circulations, originating from the tropical waves influence, are currently tracking Westward on the basin.

The first is located North of Madagascar, with a rather well-defined center near 8.5S/51.9E at 10Z. The second one is currently located South of the Chagos archipelago, also with a rather well-defined center located near 12.3S/70.6E at 10Z. However for both these weak systems, convection is only triggering along convergence lines in the southern semi-circle, where the surface convergence with the environmental trade winds is the strongest. Under the conjugated effects of a lack of equatorward convergence, m
id-level dry air and a moderate Easterly shear aloft, these weak lows are expected to dissipate by next Friday.

Development of a moderate tropical storm over the basin is not expected during the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

598
AWIO20 FMEE 230906

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/23 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a near equatorial trough (NET) configuration centered at 5oS to West of 60oE. Further to the east of the basin, the trough is located more to the south, allowing a more direct trans-equatorial flow to penetrate, favoring the convergence east of Diego-Garcia. The convective activity is moderate to strong also in the zone of slowing trade winds on the southern side of this NET. Over the next few days, convective activity should continue, with no zone susceptible to the development of a clockwi
se circulation.

Development of a moderate tropical storm over the basin is not expected during the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

784
AWIO20 FMEE 241139

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/24 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Neant.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The convective activity observed on the basin is more significant, compared to the last 24 hours.

It is moderate to strong over the northeast quarter of the basin and is mainly located:

- at the low level convergence of the trade winds, in the southern semicircle of a clockwise circulation, approximately centered southeast of Agalega by 12oS / 62oE (according to SCATSAT-1 swath at 0330UTC). The circulation is quite elongated with average winds of 25kt, in its southern part.

- Northeast of Rodrigues, centered 12oS between 67oE and 74oE, only along a low layer convergence line, where the convergence is the most significant with the trade winds flow.

The low situated southeast of Agalega currently benefits good environmental conditions in altitude. However, in low layers, the supply by the transequatorial flow remains insufficient to ensure its good development.

This vortex, which is expected to move towards the Seychelles archipelago over the next few days, will encounter very unfavorable environmental conditions as early as tomorrow, which will thwart its development (intrusion of middle dry air and a moderate to strong northeastern wind shear aloft in its southern part).

Also, over the next few days, convective activity should continue without any zone susceptible to the development of a low pressure circulation.

This scenario is also considered by European and American deterministic and ensemble models.

Development of a moderate tropical storm over the basin is not expected during the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

462
AWIO20 FMEE 261052

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/26 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


On the basin, convection is concentrated along a zonal convergence line located around 7/8S between 45E and 70E. A Mixed Rossby-Gravity wave is circulating over the Western half of the basin and allowed the emergence of a temporary transequatorial flow that convergences quite nicely with the trade winds on the polar side, thus forming a monsoon-trough-like pattern (MT). On the axis of this MT, convection is strong but recent scatt. data did not reveal any well-defined closed circulation nested within the MT
. Over the next days, despite the lasting good low-level convergence, no significant development is expected in the area.

Indeed, a deep upper trough should come up into the tropical region and establish a strong westerly shear on the area. Meanwhile, a dry MJO phase should shift from Africa on the Western part of our basin, favoring large-scale subsidence and dry mid-levels.

On the far East of the basin, West of the Cocos Islands, a weak system is currently struggling with a moderate North-North-Easterly wind shear. This morning ASCAT-B swath showed an elongated circulation with winds of 10/15kt, deep convection triggering only within the southern semi-circle and a center located near 9.7S/91.3E. Over the next days, with no improvement in the upper environment and a decrease in equatorward low-level convergence, no available guidance suggest a strengthening of this system. It s
hould enter our AoR as a weak clockwise circulation, drifting Westward on the Northern side of the subtropical high pressure belt. Please refer to BOM's Tropical Cyclone Outlook nb IDW10800 for further information.

There is no risk of a tropical storm forming or entering our basin over the next five days.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

762
AWIO20 FMEE 271150

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/11/27 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The circulation of a Rossby equatorial wave and a mixed Rossby-Gravity wave over the western half of the basin favours moderate convective activity, currently located along a line oriented 10oS/45oE - 00oS/77oE.

Convection in the southern part of this line is linked to the slowing down of the trade winds, while that in the eastern part of the basin is explained by the acceleration of the equatorial westerly flow.

This morning's scatterometer swaths do not show a well-defined closed clockwise circulation within this convective activity.

Over the next few days, no significant development is expected due to unconducive environmental conditions. The supply of low level convergence on the equatorial side will gradually weaken over the weekend, but above all a deep upper trough should come up into the tropical field will establish a strong westerly shear on the zone, accompanied by middle dry air aloft.

On the far east of the basin, west of the Coco Islands, a weak system is currently stuggling with a moderate east-north-easterly wind shear. The scatterometer swaths of the morning remain partial; the last one, dating from yesterday afternoon (SACAT-SAT1 of 1330Z) reveals an elongated circulation, with winds of 20 knots maximum. The convection triggered by this low has decreased since yesterday, with a centre located near 11.5S/92E at 0600UTC.

Over the next few days, this vortex will continue to encounter unconducive environmental conditions to its intensification. In low level the wind will gradually weaken on the equatorial side of the vortex over the period. Aloft, the disturbed zone will evolve along the northern edge of a ridge, causing it to undergo regular wind shear, moderate to strong, from the northeast to the east.

Finally, this vortex should enter in a weakened form over our AoR by drifting westward on the northern face of the subtropical high pressure belt. No available guidance suggest a strengthening of this system for the next few
ays.

Please refer to BOM's Tropical Cyclone Outlook nb IDW10800 for further information.

There is no risk of a tropical storm forming or entering our basin over the next five days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.

#
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

943
AWIO20 FMEE 011219

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/01 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a near-equatorial trough (NET) pattern, axed between 5S and 10S east of 70E.

The convective activity is now rather localized in the northern part of the NET and in the vicinity of a Disturbed Weather Zone that entered yesterday on the North-Eastern part of our area of responsibility.

Zone of Disturbed Weather over the North-Eastern part of the basin:

During the last 24 hours, the system has not shown any sign of intensification: the circulation center appears much less defined and the upper levels divergence is less marked. The system is estimated at 11 UTC around 10oS and 85.5oE with winds at 20/25 kt and minimum pressure at 1006 hPa. The system is currently moving towards the West-Northwest at about 8 kt. Environmental conditions are currently marginal for development: Dry air in the middle troposphere is present within the circulation. On the other
hand, the convergence of low layers is rather poor on the equator side with a westerly flow feeding primarily the system developing in the Bay of Bengal. Finally, a moderate easterly constraint is present as the system evolves just north of the upper ridge.

Over the next few days, environmental conditions is expected to gradually improve. Vertical wind shear is expected to decrease with the northward motion of the upper levels ridge. Under the influence of an equatorial Rossby wave entering from the east of the basin, low levels cyclonism and convergence will gradually improve and by Friday or Saturday, the system should be in a very moist mid-levels environment. It should by that time take advantage of the important oceanic potential available in this part of
the basin to finalize the cyclogenesis process.

The risk of a tropical storm formation is thus increasing later this week on the east side of the basin, however the timing of this cyclogenesis differs significantly among the deterministic and ensemble numerical guidance. The system should move more slowly over the next few days within the NET before moving generally South-Westwardsfrom Saturday or Sunday.

The risk of a tropical storm forming over the North-Eastern basin becomes low from Friday, then moderate on Sunday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

947
AWIO20 FMEE 021004

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/02 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin has a near equatorial trough (NET) configuration, oriented towards 7S east of 65E. Within this NET, a large circulation is noticeable using ASCAT swath data from 0301UTC defining a disturbed zone whose center can be estimated around 8oS/83.5oE with maximum winds of about 25kt in the northern part of this circulation, even 30kt under convection.

The convective activity over the basin is mainly focused in the northern part of the NET and in the vicinity of the zone of disturbed weather mentioned
bove.

On the extreme North-East of the basin :

The environmental conditions are still not favourable for a rapid development and it will therefore be necessary to wait for the low-level circulation to consolidate under a more favourable environment for intensification to be possible. This improvement is expected to take place over the next few days, defining a moderate risk of tropical storm formation within 4 to 5 days. Deterministic and ensemble guidance differs from that of possible intensification, but the trend is towards a low intensity.

Development of a moderate tropical storm is moderate from Sunday onwards, in the North-East of the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

526
AWIO20 FMEE 031210

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/03 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin presents a Near Equatorial Talweg (NET) pattern, oriented towards 7S east of 56E.

Within this NET, the convective activity is more concentrated than in the last 24 hours, particularly near the disturbed zone monitored over the last few
ays.

The data from the ScatSat1 of 0230UTC depicts a large elongated disturbed zone without a well-defined center. Maximum winds of about 25/30kt on either side of the axis NET.

On the North-East of the basin :

In the next two days, the environmental conditions are conducive for the development of the disturbed zone.

The supply by the equatorial west flow and the trade winds remains favorable, with a wind shear aloft that will remain low to moderate. In addition, the system will benefit from maximum oceanic potential as it progresses towards the southwest.

The majority of deterministic models are in agreement with the development of this system during this period, except the european model.

From Sunday onwards, environmental conditions are expected to deteriorate, with the intrusion of dry air in the middle troposphere, associated with vertical wind shear from the North.

Developpement of a moderate tropical storm becomes moderate from tomorrow onwards, in the North-East of the basin and becomes weak again at the beginning of next week.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

680
AWIO20 FMEE 051207

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/05 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


East of 55E, the basin remains in a near-equatorial trough (NET) pattern, undulating between 5oS and 10oS. Convective activity also remains mainly located on the eastern half of the NET (east of 80oE) but also on the northern edge of the NET bordering the well-established equatorial westerlies in the 3oN-3oS band. Within this area, a Zone of Disturbed Weather is still present over the extreme North-East of the basin.

Zone of Disturbed Weather East of the Chagos archipelago :

During the last 24 hours, convective activity has strengthened within the circulation without however showing obvious signs of curvature and being marked by an Easterly shear constraint estimated at nearly 30 kt according to CIMSS data. The center of the low pressure circulation, rather well defined on the morning Ascat data in the morning but poorly defined on microwave imaging, is estimated at 09Z around 7.9oS and 87.2oE moving at 7 kt in a general east-southeast direction. Maximum winds are estimated at
20 kt (Ascat B and C this morning) and central pressure at 1004 hPa.

Tonight or tomorrow, the system should gradually move southward and then southwest under the gradual influence of the subtropical ridge further south. On this trajectory, the environmental conditions are favorable until Monday with a significant oceanic potential, an expected decrease in easterly shear accompanied by a well marked upper levels polewards divergence and a moist mid-levels environment. However, from Monday onwards, under the effect of a north-westerly mid-troposphere shear, dry air should wrap
into the circulation and stop the strengthening trend. From Tuesday, the residual circulation should drift westward on the northern face of the subtropical high pressure.

Deterministic models are not unanimous in suggesting further deepening up to the tropical storm stage, and ensemble forecasts still suggest a moderate risk. With a system globally analyzed too far south compared to its real position, the uncertainty remains high on the possibility of cyclogenesis despite the relatively short time frame.

The risk of a tropical storm forming over the Northeast of the basin remains moderate tomorrow, then becomes low from Monday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

100
AWIO20 FMEE 061016

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/06 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no001/3 et WTIO30 FMEE no001/3/20202021 on Tropical Disturbance issued at 06UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a near equatorial trough (NET) configuration oriented towards 8oS east of 55o, extending towards 11oS near the tropical disturbance 03/20202021, described in the various warnings issued at 06UTC. The strong convective activity is mainly focused near the tropical disturbance. It is also present on the north side of this NET in the zone of deceleration of the flow.

Tropical Disturbance 03-20202021 :

Position at 09UTC: 12.6oS/86.4oE
Maximum wind: 25kt
Central pressure: 1001hPa
Current movement: South-Southwest at 8kt

For the next 5 days, there is no risk of formation of another moderate tropical storm over the bassin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

426
AWIO20 FMEE 071118

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/07 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no004/3 et WTIO30 FMEE no004/3/20202021 on Moderate Tropical Storm BONGOYO issued at 06UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a near equatorial trough (NET) pattern along 8oS east of 55o. Convective activity is moslty lcoated on the northern side of the NET and near the Moderate Tropical Storm BONGOYO.

Moderate Tropical Storm BONGOYO :

Position at 10UTC: 15.0oS/81.3oE
Maximum wind: 40kt
Central pressure: 995hPa
Current movement: South-Southwest at 12kt

For the next 5 days, there is no risk of formation of another moderate tropical storm over the bassin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

494
AWIO20 FMEE 081020

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/08 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no008/3 et WTIO30 FMEE no008/3/20202021 on Severe Tropical Storm BONGOYO issued at 06UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The convective activity is mainly present in the monsoon flow buffer area and around the Severe Tropical Storm BONGOYO.

Severe Tropical Storm BONGOYO :

Position at 10UTC: 17.9oS/77.8oE
Maximum wind: 55kt
Central pressure: 988hPa
Current movement: Southwest at 11kt

For the next 5 days, there is no risk of formation of another moderate tropical storm over the bassin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

605
AWIO20 FMEE 131158

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/13 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a poorly defined Monsoon Trough (MT) pattern east of 70oE. The trans-equatorial flow, present over the entire basin, is rapidly oriented in a westerly flow and does not reach latitudes south of 5-6oS east of 50oE. It thus converges very little with the trade winds, which do not reach latitudes north of 12oS. The axis of the MT is in fact a broad buffer zone (ie light winds) between 6-12oS. In this context, the thunderstorm activity is essentially present on the northern side of the MT within
the westerly flow. It remains more important over the North-Eastern basin without any suspicious area.

During the week, the filtering of the upper levels divergence anomalies at 200 hPa (velocity potential) shows that a Kelvin wave should cross the basin from West to East. It should encounter a westward propagating signal associated with the Rossby Gravity Mix and, to a lesser degree, the Rossby Equatorial wave. In this context, the low levels convergence should slowly improve within the MT later next week, without any risk of cyclogenesis by Friday.

Remnant low BONGOYO:

Scatterometric data from this morning show that the system has degenerated into a low-levels trough over the last 24 hours. The axis is located at 11:30 UTC around 64oE. It continues its westward movement and will be associated with moister trade-winds conditions over the Mascarene Islands during the next few days.

During the next 5 days, the development of a moderate tropical storm is not expected.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

776
AWIO20 FMEE 141202

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/14 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin is in a poorly defined Monsoon Trough (MT) pattern East of 55oE. The trans-equatorial flow, depicts East of 41oE, is rapidly oriented as a West-North-Westerly flow and does not drift South of 7oS East of 73oE. The monsoon flow struggles to converge with the trade winds flow, which has difficulty in moving north of 12oS.

The axis of the MT thus observed is in fact a buffer zone, quite wide between 7-12oS.

In this particular context, the conductive activity is mainly present north of the MT, in the zone of slowing down of the West-North-Westerly flow. The convective activity is also moderate on the North-East part of the basin without suspicious zone.

During the week, the filtering of upper-levels divergence anomalies at 200 hPa (velocity potential) shows that a Kelvin wave should cross the basin from West to East. It should encounter a westward propagating signal associated with the Mixed Rossby Gravity and, to a lesser degree, the Rossby Equatorial waves. In this context, the low layers convergence should slowly improve within the TM in the second half of the week, without any risk of cyclogenesis by Saturday.

The latest deterministic models suggest an increasing risk of cyclogenesis within the MT East of 60oE, but rather at 5/10 days.

BONGOYO residual depression:

This morning's ASCAT data show that the system is reduced to a low-level trough moving on the northern edge of the Mascarenes High. The axis of the system is located at 10:15 UTC around 57oE.

It moves westwards, sliding to the north of the Mascarenes islands and will bring from tomorrow onwards with moisture trade winds conditions over the Mascarenes Islands.

During the next 5 days, the development of a moderate tropical storm is not expected.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

464
AWIO20 FMEE 161130

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/16 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is mainly in a monsoon trough pattern near 10S, with a rather well established monsoon flow West of 60E. Convection is mainly located on the equatorial side of the MT, where the monsoon flow slows down. Two main vorticity areas are located on each side of the MT, in the North-East of the Farquhar islands and along the Eastern border of the basin. However, this morning scatt data did not reveal any well defined closed clockwise
irculation.

Over the next days, under the influence of a moderate tropical waves activity (weak Kelvin wave and an Equatorial-Rossby), the monsoon flow should become more zonal at the equator. The MT should thus remain rather ill-defined. The most recent model runs are now suggesting the emergence of a large clockwise circulation (monsoon low) over the next week-end in the North-East of the Mascarenes. However, the low-level convergence is limited equatorward. Furthermore, from Monday, a weak Northerly shear constraint
associated to mid-level dry air advections should significiantly limit the potential of cyclogenesis.

The most recent ensemble data is in good agreement with this scenario. However, given the variability seen amongst the ensemble and deterministic guidance over the last 48 hrs, the medium-range forecast uncertainty appears moderate.

During the next 5 days, the development of a moderate tropical storm is not expected.

Overland depression over Southern Africa :

Compared to yesterday, convection is now well concentrated around a better-defined clockwise circulation located near 18S/23E, near the borders of Zambia, Zimbabwe, Botswana, Namibia and Angola. Benefiting from an excellent upper divergence from next Friday, convection should continue to develop and could lead to the formation of an associated surface low.

While drifting West-South-Westward over the week-end, this overland depression could bring significant rainfall on these regions and especially over the northern parts of Botswana and Namibia.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

048
AWIO20 FMEE 170929

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/17 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is mainly in a monsoon trough pattern near 10S, with a rather well established monsoon flow West of 60E, a more zonal flow east of 65E, becoming monsoon flow east of 80E. Convection is mainly located on the southern side of the MT, in the trads flow. Two main vorticity areas are located on each side of the MT, in the North-East of the Farquhar islands and along the Eastern border of the basin. However, this morning scatt data did not reveal any well defined closed clockwise circulation in the North-East of the Farquhar islands.

Closed clockwise circulation along the Eastern border of the basin :

the last satelite imagery shows a well defined vortex completly exposed near 7.4S/86.4E. according to the last scatt data ASCAT-B at 04h30utc, winds are about 15/20kt, and according CIMMS data the eastern vertical shear is about 30kt. upper level conditions remain unfavorable over the next days.

Over the next days, under the influence of a moderate tropical waves activity (weak Kelvin wave and an Equatorial-Rossby), the monsoon flow should become more zonal at the equator. The MT should thus remain rather ill-defined. The most recent model runs are now suggesting the emergence of a large clockwise circulation (monsoon low) over the next week-end in the North-East of the Mascarenes. However, the low-level convergence is limited equatorward. Furthermore, from Monday, a weak Northerly shear constraint
associated to mid-level dry air advections should significiantly limit the potential of cyclogenesis.

The most recent ensemble data is in good agreement with this scenario. However, given the variability seen amongst the ensemble and deterministic guidance over the last 48 hrs, the medium-range forecast uncertainty appears moderate.

During the next 5 days, the development of a moderate tropical storm is not expected.

Overland depression over Southern Africa :

As yesterday, convection is well concentrated around a better-defined clockwise circulation located near 18S/23E, near the borders of Zambia, Zimbabwe, and Botswana, with the main activity now located on the northern part of Botswana. Benefiting from an excellent upper divergence from next Friday, convection should continue to develop and could lead to the formation of an associated surface low.

While drifting West-South-Westward over the week-end, this overland depression could bring significant rainfall on these regions and especially over the northern parts of Botswana and Namibia.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

747
AWIO20 FMEE 181211

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/18 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


Most of the basin remains in a monsoon trough (MT) pattern around 10S with a well established monsoon flow east of 60E. Associated convective activity is generally low to moderate. It is located near three vorticity zones present in the MT: one at the western edge of the MT around 9S/51E, another one southwest of the Chagos archipelago around 11S/68E and the third one on the extreme northeast of the basin. Currently, only the easternmost zone is a suspect area.

Tropical disturbance at the Northeast boarder of the basin :

During the last 24 hours, the minimum monitored since yesterday continued to show a well-defined low-level circulation, associated with sporadic convective activity present in the western semicircle due to a rather strong eastern vertical shear. At 09Z the center is located at 8.5oS and 88oE. The maximum winds are estimated at 20/25 kt and can locally reach 30 kt in the northern semicircle (see scatsat of 0202Z this morning). The minimum pressure is estimated at 1005 hPa. This system is moving southeastward
at about 5 kt.

Over the next few days, while the system is expected to slow down and evolve close to the eastern boarder of our basin. Environmental conditions could become temporarily favorable by Sunday with a decrease in vertical shear and an improvement in the equatorward upper levels divergence. The low levels convergence, if it remains good on the South side, remains indirect on the North side with a rather zonal monsoon flow. The latest deterministic and ensemble guidance do not propose any significant deepening of
this system.

Given the small size of the system, which can lead it to experience rapid variations in intensity, a very low risk of tropical storm formation cannot be completely ruled out.
The risk of a tropical storm formation becomes very low over the extreme North-East of the basin during the next 2 days.

Over the next few days, under the influence of a rather sensitive wave activity (crossing Kelvin wave and Equatorial-Rossby wave at the beginning of next week), a better defined low pressure system should gradually take place during the next 2 to 3 days within the vorticity zone located in the MT southwest of the Chagos archipelago. Although the environment is favorable at the upper levels for the development of a system (low shear and very good divergence on the south side), uncertainty remains about the o
rganization in the low levels. There are indeed notable differences between the 2 reference models (GFS vs IFS) to succeed in efficiently converging monsoon and trade winds flows within an initially rather large MT.

The GEFS and EPS ensemble data show similar discrepancies with a very weak signal for the next 5 days on EPS and more important on GEFS. Note that the EPS signal is then increasing over the 5-10 day period.
Over the next 5 days, the risk of a moderate tropical storm formation becomes low from Wednesday onwards.

Overland Depression over Southern Africa :

This system remains at the stage of a rather poorly defined low pressure area located today over northern Botswana. It remains associated with locally heavy thundery rains that will shift southwestward over the weekend into the northern parts of Namibia.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

162
AWIO20 FMEE 191046

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/19 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a monsoon trough (MT) configuration oriented towards 9S with a well-established monsoon flow east of 60E. The convective activity is globally moderate in this TM. The convective activity is located near two areas of low-level circulation within the MT and described below.

Tropical disturbance at the Northeast boarder of the basin :

After an enhanced convection near the circulation center last night, the convection collapsed again, revealing the circulation center around 9.3E/89.8S to 9UTC. The last ASCAT swath passes allowed to locate winds of about 25kt on the northern part of the circulation reaching 30kt very locally yesterday around 1500UTC and with slightly lower values today at 0209UTC. This system will remain east of 90E for the next few days. The environmental conditions (mainly the rather strong easterly wind shear analyzed b
y the CIMSS and located at the northern edge of the system) being and remaining unfavorable, this system does not present any potential for intensification.

Over the next 5 days, there is no longer any risk of a moderate tropical storm formation in this area.

Zone of disturbed weather in the North-East of the Mascarene Islands :

In a context of favorable wave activity (crossing of a Kelvin wave and an Equatorial-Rossby wave at the beginning of next week), the large low-level circulation currently present to the North-East of the Mascarene Islands around 11.3S/66E is under the influence of an environment favorable to its development. However, the circulation must first be consolidated over the next two days. An uncertainty in the potential for intensification is still noticeable in the different reference models (GFS vs IFS), leavin
g a less marked potential for the case of the European Center model (IFS) with a drier environment from Monday. It should be noted that the EPS ensemble forecast leaves a slightly higher risk of a tropical storm formation than previously. In terms of intensity forecast, this system should therefore remain at the lower limit of the Severe Tropical Storm threshold over the next 5 days.

Over the next 5 days, the risk of a moderate tropical storm formation becomes moderate from Tuesday onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

320
AWIO20 FMEE 200930

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/20 AT 1200 UTC

PART 1:

WARNING SUMMARY:

Bulletins WTIO20 FMEE no001/4 and WTIO30 FMEE no001/4/20202021 on zone of disturbed weather 04/20202021 issued soon at 12UTC

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a monsoon trough (MT) configuration oriented towards 10S with a well-established monsoon flow east of 60E. The convective activity is globally moderate to strong in this MT and is located in a privileged location on the South face and close to the two zones of low-level circulation present within the MT and described below.

Tropical disturbance at the Northeast boarder of the basin :

The circulation has now passed into the area of Australian responsability. This system could return to our area of responsibility in the next few days, but does not present any potential for intensification during this period.

Zone of disturbed weather in the North-East of the Mascarene Islands :

From today at 12UTC, this zone of disturbed weather is monitored by the RSMC.

Position at 09UTC : 12.5oS/65.3oE

Maximum Wind: 20kt

Estimated central pressure: 1008hPa

Current movement : West-Southwest 4kt

Over the next 5 days, there is no risk of formation of another moderate tropical storm over the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

687
AWIO20 FMEE 211134

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/21 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no002/4 and WTIO30 FMEE no002/4/20202021 on zone of disturbed weather 04/20202021 issued soon at 12UTC

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a mixed pattern between a Monsoon Talweg (TM) and a Near Equatorial Thalweg (TPE) with a monsoon flow crossing the equator only west of 70E. Convective activity is mainly concentrated around the zone of disturbed weather 04 and in the equatorial westerly flow on the east of the basin. Over the next few days, the monsoon flow is expected to strengthen over the entire basin.

Overland Depression over Southern Africa :

The overland depression monitored for several days over Southern Africa is now located over central Namibia. Due to the interaction with a high altitude trough, this low should gradually disappear while moving rapidly southward, and keeping on generating heavy rains over eastern Namibia today and South Africa tomorrow.

Low at the Northeastern border of the basin :

In the Indonesian AoR, located at 10Z around 9.0S/91.9E, a low pressure system is still present with maximum winds of around 20kt. Environmental conditions are expected to remain unfavorable for most of the week with moderate to strong easterly and then north-easterly shear. Although it could persist in this sector, this minimum does not present a risk of cyclogenesis for now.

Zone of disturbed weather North-East of the Mascarene Islands :

Position at 10UTC : 13.4S/64.2E

Maximum Wind: 25kt

Estimated central pressure: 1004hPa

Current movement : South-West 4kt

For further information, please refer to WTIO30 issued at 12Z

Over the next 5 days, there is no risk of formation of another moderate tropical storm over the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

454
AWIO20 FMEE 221028

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/22 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no003/4 and WTIO30 FMEE no003/4/20202021 on zone of disturbed weather 04/20202021 will be issued soon at 12UTC

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a mixed pattern between a Monsoon Talweg (TM) and a Near Equatorial Thalweg (TPE) with a monsoon flow crossing the equator only west of 65E. Convective activity is mainly concentrated around the zone of disturbed weather 04 and in the equatorial westerly flow on the east of the basin. Over the next few days, the monsoon flow is expected to strengthen over the entire basin.

Overland Depression over Southern Africa :

The overland depression monitored for several days over Southern Africa is now located on the border between Namibia, Botswana and South Africa. Due to the interaction with a high altitude trough, this low should gradually disappear while moving rapidly southward, and keeping on generating heavy rains mainly over South Africa today.

Low at the Northeastern border of the basin :

In the Indonesian AoR, located at 06Z around 9S/92E, a low pressure system is still present with maximum winds of around 20kt. Environmental conditions are expected to remain unfavorable for most of the week with moderate to strong easterly and then north-easterly shear. Although it could persist in this sector, this minimum does not present a risk of cyclogenesis for now.

Zone of disturbed weather North-East of the Mascarene Islands :

Position at 06UTC : 13.2S/62.3E

Maximum Wind: 25kt

Estimated central pressure: 1004hPa

Current movement : West South-West 4kt

For further information, please refer to WTIO30 issued at 12Z

Over the next 5 days, there is no risk of formation of another moderate tropical storm over the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

562
AWIO20 FMEE 231048

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/23 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Bulletins WTIO20 FMEE no004/4 and WTIO30 FMEE no4/4/20202021 issued at 06 UTC on Tropical Depression no04/20202021. Next warning will be issued at 12 UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern, axed along 10oS and associated with 2 low-pressure areas: tropical depression no04 at the western end of the MT and an area of disturbed weather located at the eastern end of the MT, in the Indonesian area of responsibility close to 90oE. These two lows contain most of the convective activity over the basin. However, convective activity is also present north of the MT between 65oE and 90oE.

Tropical depression no4/20202021 to the North-East of the Mascarene Islands :

Position at 0930 UTC : 14.7oS / 60.6oE

Maximum 10 min winds: 30 kt

Estimated central pressure: 999 hPa

Forward motion: Westwards at 5 kt

For more information refer to bulletins WTIO20 and WTIO30 issued at 06Z and followings.

Over the next 5 days, the likelihood that this system will become a moderate tropical storm is high.

Zone of Disturbed Weather at the North-Eastern boarder of the basin :

This low pressure area, which remains located in the Indonesian area of responsibility, has not shown significant signs of intensification during the last 24 hours. It has changed little since yesterday and is located near 9.1oS and 91.3oE (see Ascat of 0341Z). This system should evolve in the Indonesian area until the weekend before a possible come back west of 90oE at the beginning of next week. In an environment that will remain essentially easterly sheared throughout the period, the system has little or
no potential for development and it is not yet associated with a risk of cyclogenesis over the next 5 days.

During the next 5 days, there is no risk of a moderate tropical storm forming over the Northeastern basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

285
AWIO20 FMEE 271012

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/27 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) configuration over the entire width of the basin and oriented towards 10oS.

Convection activity is mainly located on the northern face of this MT and close to a weak low level circulation to the southeast of the Chagos and at the edge of the basin to the southeast of the circulation in the Australian basin and has been monitored for several days around 10oS/93oE according to the BOM monitoring bulletin of 0600 UTC (Tropical Cyclone Outlook for the Western Region - IDW 10800).

Depression on land CHALANE on Madagascar :

Position at 0900 UTC : 18.3oS / 47.2oE

Maximum wind over 10 minutes: 20/25 kt

Estimated central pressure: 1007 hPa

Forward motion: West-South-West at 10 kt

The depression on land is expected to emerge on the sea in 24 hours on the west coast of Madagascar. In a rather favorable environment, some models forecast a re-intensification of Chalane. In which case, the system will again be monitored by regular bulletins issued by the RSMC of Reunion Island.

During the next 5 days, the risk of re-intensification of the depression on land Chalane into a moderate tropical storm in the Mozambique Channel is considered moderate to strong from Tuesday onwards.

Area of Disturbed Weather near the North-Eastern boarder of the basin :

The low pressure area followed by the BOM bulletin of 0600 UTC (Tropical Cyclone Outlook for the Western Region - IDW 10800) should continue to move westward and enter our basin during the day on Monday. Future environmental conditions remain rather unfavorable for its intensification. Deterministic and ensemble guides are generally in agreement with this scenario.

During the next 5 days, the risk of a moderate tropical storm forming on the extreme east of the basin is considered very low from Wednesday onwards.

Southeast of the Chagos archipelago

The Scat-Sat1 swath at 0230 UTC and the partial ASCAT swath at 0430UTC show the presence of a large elongated low-level circulation associated with winds of around 15kt. The center of this ill-defined circulation is located around 10.7oS/72.9oE. Over the next few days, the fairly favourable environmental conditions are expected to continue and could lead the low-level circulation to become better defined and closed within 2 days.

During the next 5 days, the risk of a moderate tropical storm forming near the Chagos archipelago becomes moderate from Wednesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

825
AWIO20 FMEE 281203

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/28 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO24 and WTIO30 to be issued on Tropical Depression CHALANE at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern over the entire width on a axis along 10oS.

Convection activity is mainly located near the three areas monitored for several days : tropical depression CHALANE in the Mozambique Channel, and the two suspect areas near Diego-Garcia and the eastern border.

Tropical Depression CHALANE:

Position at 0900 UTC : 20.2oS / 43.1oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 1001 hPa

Forward motion: West-South-West at 10 kt

For further information, please refer to WTIO24 and WTIO30 to be issued at 12Z and following.

Area of Disturbed Weather near the North-Eastern boarder of the basin :

The low pressure area also monitored by the 0600 UTC BOM bulletin (Tropical Cyclone Outlook for the Western Region - IDW 10800) is located around 10.5S/90.5E at 0930Z. It should enter our area of responsibility overnight. Maximum winds are in the range of 15 to 20kt, reaching 25kt far from the center in the southern semicircle. The inner circulation is quite broad and elongated, under the influence of a strong and persistent east-northeasterly shear at all levels. In addition, a southwestern component seems
to be present in the monsoon flow in the northern semicircle. Convergence in sector is therefore not fully effective despite a well-established monsoon flow. These unfavorable conditions limit the risk of cyclogenesis at short range.

During the course of the week, as it moves southwest, upper conditions should improve with the decrease of the shear and then by the end of the week, the increase of the divergence on the polar side ahead of an upper trough far to the south. At low levels, the trade wind flow should become more convergent from Wednesday/Thursday. However, this possible cyclogenesis is likely to be hindered by the possible simultaneous formation of another storm further west which could limit the feeding flow on the equator
ial side.

All the numerical guidance is in good agreement with this scenario but give different solutions from mid-week onwards in relation with the possible interference with the system further west. The forecast for the weekend is still very uncertain.

During the next 5 days, the risk for the development a moderate tropical storm on the eastern part of the basin becomes low from Thursday.

South of the Chagos archipelago

Latest satellite images show a low level vortex around 9.8S/70.8E at 11z, northeast of the main convective activity within which there seems to be a mid level circulation. 0404z ASCAT swath shows maximum winds reaching 15/20kt and even 25kt near the convective activity within an elongated and poorly defined circulation.

Over the next few days, the monsoon flow could become more convergent while the trade wind feed could even strengthened on Wednesday. In the upper levels, a northerly shear may increase around mid-week as well as the upper divergence ahead of a through. These conditions suggest a possible cyclogenesis, especially since the movement of the low is in the direction of the shear. At longer range, this possible deepening could also be hindered by the presence of the other suspect area further east, which could l
imit its polar feeding.

All the numerical guidance is in good agreement with this scenario but give different solutions from mid-week onwards in relation with the possible interference with the system further east. The forecast for the weekend is still very uncertain.

During the next 5 days, the risk for the development of a moderate tropical storm near the Chagos archipelago becomes low on Wednesday and moderate on Saturday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

254
AWIO20 FMEE 291120

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/29 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO24 FMEE no0023/4/20202021 and WTIO30 FMEE no 0023/4/20202021 to be issued on Severe Tropical Storm CHALANE at 06Z. Next warning at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern over the entire width of the basin and oriented towards 10oS.

The convective activity is mainly located near the three areas that have been monitored for several days: the severe tropical storm CHALANE on the southern Mozambique Channel, and the two suspect areas near Diego-Garcia and the eastern limit of the basin.

Severe tropical storm CHALANE :

Position at 0900 UTC : 19.6oS / 38.9oE

Maximum wind over 10 minutes: 50 kt

Estimated central pressure: 990 hPa

Motion: West-Northwest at 14 kt

For more information please refer to warnings WTIO21 and WTIO31 issued at 06 UTC and following.

Disturbed Zone at the North-East of the basin :

The low pressure area is located at 0900 UTC around 11.5S/87.7E and moves towards the west-southwest at 09 kt.

Maximum winds are around 20kt, locally reaching 25kt far from the center in the southern semicircle.

The estimated central pressure is 1003 hPa.

The circulation is fairly wide and elongated, under the influence of a weak to moderate east-northeast windshear.

The low level convergence in the northern semicircle is not fully effective despite a well-established monsoon flow. These environmental conditions limit the risk of cyclogenesis in the short term.

During the course of the week, as it moves west-southwest, the vortex will interact with the vortex currently present south of the Chagos, which will have the effect of thwarting low-level convergence on the equatorial side. The scenario retained by the main guidances (deterministics and ensemble forecasts) suggest that this suspicious zone will be maintained to the detriment of the one present south of the Chagos. This representation is not stabilized at the present time and could evolve with the next guid
ances.

The conditions aloft should also improve, with the decrease of the windshear and then at the beginning of the weekend the increase of the divergence on the polar side in front of an upper levels trough.

The forecast for the weekend is still very uncertain, given the complexity of the situation, with the possible interaction between these two lows.

During the next 5 days, the risk of a moderate tropical storm forming over the eastern part of the basin is considered moderate from Friday onwards.

South of the Chagos:

The last satellite images show a vortex around 10S/72.7E, moving east-southeast at 5 kt.

The surface circulation is well defined, but completely cut off from the convective activity located further southwest, under the effect of moderate easterly windshear.

Over the next few days, the low-level inflow, especially the trade winds flow, will be thwarted by the more southerly transit of the vortex located on the eastern side of the basin. This will have the effect of limiting the development of this circulation.

In addition, conditions at altitude will be unconducive, with the presence of dry air and strong shear from the North to North-East.

This scenario is envisaged by the current guidances, but there is still uncertainty about the possible interaction between the two circulations present on the basin. The forecast for the weekend therefore remains very uncertain.

During the next 5 days, the risk of formation of a moderate tropical storm near the Chagos becomes and remains low from Wednesday onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

860
AWIO20 FMEE 301134

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/30 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO24 FMEE no0027/4/20202021 and WTIO30 FMEE no 0027/4/20202021 to be issued on Moderate Tropical Storm CHALANE at 06Z. Next warning at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin is in a Monsoon Trough (MT) pattern between 46oE and 90oE and oriented towards 12oS.

The convective activity is mainly located near the three areas that have been monitored for several days: the moderate tropical storm CHALANE, which landed this morning north of the town of BEIRA, in MOZAMBIQUE, and the two suspect areas near Diego-Garcia and the eastern limit of the basin.

Moderate tropical storm CHALANE :

Position at 0900 UTC: 19.10oS / 33.60oE

Maximum wind over 10 minutes: 35 kt

Estimated central pressure: 998 hPa

Displacement: West-Northwest at 13 kt

For more information please refer to bulletins WTIO21 and WTIO31 issued at 06 UTC and following.

Disturbed Zone at the North-East of the basin :

Data from ASCAT-C swath of 0330Z, show a rather poorly defined low pressure area with an elongated circulation and winds of about 20kt in the southern semicircle. It is enduring a moderate to strong easterly windshear. The center of this low level circulation is located at 0900Z around 13S/86E and the central pressure is estimated at 1003 hPa.

South of the Chagos:

The last satellite images of 0900Z show a vortex around 12.8S/71.9E, moving east-southeast.

The last ScatSat1 swath of 0330Z describes a closed and well-defined clockwise circulation with winds of 20 to 25kt in the southern semicircle, but cut off from convective activity further southwest, under the effect of moderate to strong easterly shear.

Evolution of the two vortex over the eastern part of the basin over the next few days:

The evolution of the two circulations currently present over the eastern part of the basin is made difficult due to a very probable interaction between them. In particular, it is difficult to know which of the two will take precedence over the other, while the models are now in good agreement on a merger of the two circulations early this weekend.

The system resulting from this merger is likely to develop over the weekend. However, the windshear aloft remains significant in the eastern sector, and there is still uncertainty about the presence of dry air in the middle troposphere.

Consequently, the potential for the resulting vortex to deepen remains difficult to assess at this time.

Over the next 5 days, the risk of a moderate tropical storm forming near the Chagos archipelago is moderate from Saturday onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

110
AWIO20 FMEE 311148

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2020/12/31 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO20 FMEE no002/5/20202021 and WTIO30 FMEE no 02/5/20202021 issued on Zone of Disturbed Weather at 06Z.

Warning WTIO20 FMEE no001/6/20202021 and WTIO30 FMEE no 01/6/20202021 issued on Zone of Disturbed Weather at 00Z.Next warning at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern along 11oS.

The convective activity is mainly located on the northern side of the MT and near the three areas that have been monitored for several days: Overland depression CHALANE, and the two suspect areas near Diego-Garcia.

Overland depression CHALANE :

Position at 0900 UTC: 20.20oS / 25.90oE

Maximum wind over 10 minutes: 20 kt

Estimated central pressure: 1005 hPa

Movement: West-South-West at 17 kt

Since yesterday, convective activity decreased significantly near the low level center. CHALANE is moving rapidly westward. Currently over the border of Zimbabwe and Botswana, it should reach Namibia b the end of Friday, still inducing heavy rains. The remnants should dissipate next to the Namibian shores on Sunday or Monday, without any chance for a new deepening.

Zone of Disturbed Weather 05 :

Position at 0900 UTC: 13.70oS / 83.90oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 1000 hPa

Movement : West at 06kt

For further information, please refer to WTIO20 issued at 06Z and following.

Tropical Disturbance 06 :

Position at 0900 UTC: 12.10oS / 72.50oE

Maximum wind over 10 minutes: 25 kt

Estimated central pressure: 1001 hPa

Movement : Quasi-stationary

For further information, please refer to WTIO20 issued at 00Z and following.

Over the next 5 days, there is no risk that an other system becomes a moderate tropical storm in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

728
AWIO20 FMEE 011008

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/01 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO20 FMEE no006/5/20202021 and WTIO30 FMEE no 06/5/20202021 issued on Tropical Depression 05 at 06Z.

Warning WTIO20 FMEE no005/6/20202021 and WTIO30 FMEE no 05/6/20202021 issued on Tropical Depression 06 at 06Z.

Next warning at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin is in the Monsoon Trough (MT) pattern between 10.5oS and the extreme east of the basin.

The convective activity is mainly located on the northern face of the TM and close to the three areas that have been monitored for several days: the CHALANE land depression over Southern Africa, and the two systems monitored over the central and eastern half of the basin.

Depression on land CHALANE :

Position at 0900 UTC: 21.60oS / 21.10oE

Maximum wind over 10 minutes: 15kt

Estimated central pressure: 1005 hPa

Displacement: West-Southwest at 13 kt

Since yesterday, the convective activity has clearly weakened near the heart of CHALANE. The depression keeps going to track rapidly towards the west-southwest. Currently on the border between Botswana and Namibia, it is generating moderate rainfall. The remnants of this low should dissipate tomorrow Saturday, near the Namibian coastline, without risk of reintensification.

Tropical Depression 05 in the Northeast of the basin :

Position at 0900 UTC: 14.80oS / 82.00oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 1000 hPa

Displacement: West-South-West at 10 kt

For more information, please refer to bulletins WTIO21 and WTIO31 issued at 06 UTC and following.

Tropical Depression 06 South of Chagos:

Position at 0900 UTC: 11.80oS / 72.20oE

Maximum wind over 10 minutes: 30 kt loc. 35kt in SE quadrant

Estimated central pressure: 997 hPa

Travel: Quasi-stationary

For more information please, refer to bulletins WTIO21 and WTIO31 issued at 06 UTC and following.

During the next 5 days, there is no risk of another system becoming a tropical storm in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

341
AWIO20 FMEE 021045

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/02 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warning WTIO20 FMEE no010/5 and WTIO30 FMEE no10/5/20202021 issued on Tropical Depression 05 at 06Z.

Warning WTIO20 FMEE no010/6 and WTIO30 FMEE no10/6/20202021 issued on Moderate Tropical Storm 06 (DANILO) at 06Z.

Next warnings at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern axed between 10oS and 12oS from West to East, East of 50oE.

Between 70oE and 80oE, the MT goes locally down to 15oS with the presence of the tropical storm DANILO and tropical depression no05. These two systems concentrate most of the convective activity in the basin.

Over Africa, the residual low associated with CHALANE continues to be well defined and is now evolving over Northern Namibia.

Overland depression 04 (CHALANE) :

Position at 0900 UTC: 20.6oS / 16.4oE

Maximum wind over 10 minutes: 15 kt

Estimated central pressure: 1005 hPa

Motion: Westwards at 11 kt

The residual minimum is still fairly well defined. During the next 24 hours, the minimum will reach the Namibian coast where the cold waters of the South Atlantic will not allow any re-intensification. Until then, fairly significant rainfall for the region, which could exceed 50mm/24h, is expected near the center. The wet northeastern flow at the rear of the circulation will bring further locally heavy rains in the border areas between Namibia and Botswana and the southern half of Namibia.

Tropical Depression 05 over the eastern part of the basin :

Position at 0900 UTC: 14.5oS / 78.3oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 998 hPa

Motion: Westwards at 7 kt

Over the next 24 hours, there is a moderate risk that this system will become a moderate tropical storm.

For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

Moderate tropical storm 06 (DANILO) south of Chagos:

Position at 0900 UTC: 10.7oS / 72.1oE

Maximum wind over 10 minutes: 40 kt

Estimated central pressure: 992 hPa

Motion: Quasi-stationary

For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

During the next 5 days, there is no risk of another system becoming a tropical storm in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

065
AWIO20 FMEE 051005

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/05 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no021/6 and WTIO30 FMEE no21/6/20202021 issued on Severe Tropical Storm 06 (DANILO) at 06Z.

Next warnings at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon trough (MT) pattern centered between 8oS / 55oE and 15oS / 70oE.

East of 80oE, the MT goes locally down to 15oS with the presence of the low level center circulation of the severe tropical storm DANILO. Most of the convective activity occurs mainly in the vicinity of the DANILO circulation.

Severe tropical storm 06 (DANILO) south of Chagos:

Position at 0900UTC: 16.2oS / 77.0oE

Maximum wind over 10 minutes: 55 kt

Estimated central pressure: 983 hPa

Current movement: south-southeast 4kt

For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

During the next 5 days, there is no risk of another system becoming a tropical storm in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

765
AWIO20 FMEE 060954

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/06 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no025/6 and WTIO30 FMEE no25/6/20202021 issued on Moderate Tropical Storm 06 (DANILO) at 06UTC.

Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern oriented towards 8oS east of 55oE and continuing towards 11oS north of the DANILO's circulation. The western branch of this MT descends to the north of the Mozambique Channel and generates convective activity for the moment moderate in the Comoros region.

The rest of the convective activity is concentrated near the Moderate Tropical Storm DANILO and at the eastern edge of the basin.

Moderate Tropical Storm 06 (DANILO) :

Position at 0900UTC: 16.4oS / 74.8oE

Maximum wind over 10 minutes: 35 kt

Estimated central pressure: 994 hPa

Current movement: Ouest 9kt

For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

During the next 5 days, there is no risk of another system becoming a tropical storm in the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

941
AWIO20 FMEE 071125

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/07 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no029/6 and WTIO30 FMEE no29/6/20202021 issued on Tropical Depression 06 (DANILO) at 06UTC.

Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is established over the entire width of the basin and preferably west of 75oE. It feeds an Intertropical Convergence Zone on a westerly confluence pattern axed along 7oS east of 60oE, between the monsoon flow and the northern portion of the broad DANILO low pressure circulation. East of 80oE, the Monsoon Trough (MT) is reconstituting at 13-14oS.

Tropical Depression 06 (DANILO) :

Position at 0900UTC: 16.3oS / 70.5oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 995 hPa

Forward motion: West at 13 kt
For more information refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

East of the basin:

Within the reconstructed MT and in an environment where the low levels vorticity is sustained by a low frequency signal linked to La Nina and where the monsoon flow is strongly modulated by the activity of the Rossby-Gravity Mixed waves, a new low should appear during next week. According to the latest available ensemble data from GEFS and EPS, this low could have a low potential to evolve into a tropical storm, but rather in the 5-10 day time-frame.

Over the next 5 days, there is no risk of another system becoming a tropical storm in the basin.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

851
AWIO20 FMEE 081034

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/08 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no033/6 and WTIO30 FMEE no33/6/20202021 issued on Tropical Depression 06 (DANILO) at 06UTC.

Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is established on the whole width of the basin and better defined West of 75oE. It fuels an Intertropical Convergence Zone on a westerly confluence pattern axed along 7S east of 50E, between the monsoon flow and the northern half of DANILO's broad clockwise circulation. East of 75E, the Monsoon Trough (MT) is emerging again along 13S.

Tropical Depression 06 (DANILO) :

Position at 0900UTC: 16.7oS / 66.0oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 996 hPa

Forward motion: West at 11 kt
For more information refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

East of the basin:

With the gradual emergence of a new monsoon trough on the Eastern half of the basin, within a low-level environment influenced by La Nina's low-frequency signal (improved vorticity) and with a monsoon flow strongly modulated by Mixed Rossby-Gravity waves, a new low is expected to form sometime next week. However, the environmental conditions become conducive for its development only from the middle of next week. Consequently, the most recent deterministic and ensemble guidances available are suggesting a low potential for the
development of a moderate tropical storm at the 5/10j forecast lead times.

Over the next 5 days, there is no risk of an other tropical storm developing on the basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

536
AWIO20 FMEE 091159

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/09 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no037/6 and WTIO30 FMEE no37/6/20202021 issued on Tropical Depression 06 (DANILO) at 06UTC.

Next warnings at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is established on the whole width of the basin and better defined West of 75oE where it feeds a broad clockwise circulation in which DANILO is. East of 75E, the Monsoon Trough (MT) is emerging again along 10S.

Remnant Low 06 (DANILO) :

Position at 0900UTC: 17.7oS / 63.5oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 1001 hPa

Forward motion: West at 6 kt
For more information refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and followings.

East of the basin:

With the gradual emergence of a new monsoon trough on the Eastern half of the basin, within a low-level environment influenced by La Nina's low-frequency signal (improved vorticity) and with a monsoon flow strongly modulated by several tropical waves (Equatorial Rossby/Mixed Rossby-Gravity/....), several areas are monitored.

Within the Australian AOR, a low is stated in the Tropical Cyclone Outlook for the Western Region from BOM, near 16S/100E. A vorticity area also lies near 10S/86.6E according to the latest images.

These two minimums do not pose a risk of cyclogenesis at short range given the current lack of convergence of the monsoon flow. However, at longer range, thanks to an improvement of the monsoon flow convergence, a low may form and start intensifying under the upper ridge. Numerical guidance is far from an agreement on a scenario, but all models suggest a chance for deepening for the end of next week.

Over the next 5 days, the risk of development of a moderate tropical storm becomes very low on Thursday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

011
AWIO20 FMEE 101054

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/10 AT 1200 UTC

PART 1:

WARNING SUMMARY:


PART 2 :
TROPICAL WEATHER DISCUSSION:

The monsoon flow is established over the entire width of the basin and preferentially west of 75E where it feeds a broad southeast/northwest facing between 20oS/53oE and 9oS/90oE. At the extreme west of this trough, the remnant low DANILO drifts to the east of the Mascarene archipelago.

Remnant low 06 (DANILO) :

Position at 0900UTC : 18.9oS/60.0oE

Maximum wind over 10 minutes: 25 kt

Estimated central pressure: 1003 hPa

Current movement: West-Southwest 8 kt

For more information please refer to bulletins WTIO21 and WTIO31 issued at 06 UTC and following.

East of the basin:

With the reconstruction of the monsoon trough on the eastern part of the basin, in an environment where the vorticity of low layers is supported by a low frequency signal and where the monsoon flow is strongly modulated by multiple wave activity (Equatorial Rossby/MRG/...), several areas are under
urveillance.

In the Australian area, a vortex is followed by the Tropical Cyclone Outlook for the Western Region, south-southwest of the Cocos Islands. This minimum is noticed on the last visible images around 18S/94E.

Also, on the extreme Northeast of the basin, a low layer clockwise circulation, quite elongated, is visible at 0900Z, around 10oS/86.7oE.

These two minima do not present any risk of cyclogenesis in the short term, notably due to the current weak lower Level convergence on the equatorial side. However, at the end of the period, with the strengthening convergence of the monsoon flow, a minimum could form under the high ridge, to the northeast of the basin. Deterministic and ensemble models agree enough on this scenario to suggest a risk of cyclogenesis in the long term.

Over the next 5 days, the risk of another moderate tropical storm formation becomes low from Thursday onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
x
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

173
AWIO20 FMEE 111048

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/11 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 FMEE no45/6 and WTIO30 FMEE no44/6/20202021 issued on remnant low 06 (DANILO) at 06UTC.

Next warnings for only WTIO30 FMEE at 12UTC.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin presents a monsoon trough (MT) configuration centered between 6oS/55oE and 11oS at the eastern end of the basin. The convective activity is moderate to strong on the northern face of this MT but also close to the African coast at the level of the monsoon flow on the northern part of the Mozambique Channel. At the eastern edge of the basin, a large low-pressure area defines the end of the MT where convective activity is strong. Further south of this zone, convective activity is also noticeable in t
he eastern sector of a low pressure circulation followed by the Tropical Cyclone Outlook for the Western Region of the Australian Basin yesterday.

Residual Depression 06 (DANILO) :

Position at 0900UTC: 19.7oS/57.9oE

Maximum wind over 10 minutes: 20 kt

Estimated central pressure: 1006 hPa

Current movement : West-South-West 6 kt

For more information refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and following for WTIO30.

Low level clockwise circulation East of the basin:

Position at 0900UTC: 19.5oS/86.1oE

Maximum wind over 10 minutes: 30 kt

Estimated central pressure: 1007 hPa

Current movement : West 20 kt

Yesterday, in the Australian zone, the minimum is now in the South-West Indian Ocean basin under the responsibility of the RSMC of Reunion Island. This circulation presents winds of about 30kt in the South sector (locally 35kt due to gradient effect and rapid movement). This circulation evolves in a sheared environment which will not allow it to remain more than 24 hours.

Large low-level clokcwise circulation to the East of the basin:

A low-level clockwise circulation, quite elongated, is visible at 0900UTC, around 11.5oS/87.3oE. The partial ASCAT swath of 0339UTC provides maximum winds of about 20kt. In an environment that will evolve favorably (strengthening of the monsoon flow and wind shear remaining low), deterministic and ensemble models agree enough on this scenario to propose a risk of cyclogenesis in the long term.

Over the next 5 days, the risk of another moderate tropical storm formation becomes moderate from Friday onwards.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

184
AWIO20 FMEE 131222

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/13 AT 1200 UTC

PART 1:

WARNING SUMMARY:


PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin is currently in a Monsoon Trough (MT) pattern, East of 65oE. On the East side of the basin, the flow at the Equator becomes westerly under the influence of multiple wave activity (propagation of a Rossby Equatorial wave / low frequency wave and MJO wave). The passage of the Rossby Equatorial wave has notably contributed to trigger the formation of two cyclonic gyres on both sides of the Equator. South of the Equator, the one located in our AoR, is nested within the MT and has a significant cyclogenesis potential (see below).

West of 65oE, the convective activity is weak and is concentrated in the slowing down of the monsoon flow, especially northeast of Cap d'Ambre, as well as along the northwest coast of Madagascar, between Mayotte and Madagascar, subject to the diurnal cycle.

The residual depression DANILO, dissipated last night northwest of Reunion Island.

Depression circulation east of Rodrigues Island:

Position at 0900UTC: 19.6S/68.9E

Maximum wind over 10 minutes: 15kt

Estimated central pressure: 1009 hPa

Current movement: West 21 kt

With strong westerly shear aloft and middle-level dry air, the circulation is now dissipating.

Broad low level clockwise circulation southeast of the Chagos archipelago: Position at 0900UTC : 13S/79E
Maximum wind over 10 minutes: 25kt
Estimated central pressure: 1002 hPa
Current movement: West-Southwest 17 kt

The partial ScatSat-1 swath of this morning, showed a poorly defined and fairly elongated low pressure circulation in an East-West axis. Over the next few days, this low level circulation will encounter environmental conditions moderately favorable for its development. The convergence of low layers on the polar side will strengthen. Upper environmental conditions will be conducive, at the northern margin of the high ridge, with the absence of dry air aloft and moderate wind-shear in the Eastern sector. From
Friday onwards, the upper level divergence will set up on the equatorial side of the system. The cyclogenesis process could thus take shape in the next few days. All the available guidance (ensemble and deterministic) propose a cyclogenesis in the second half of the week. Initially, the system should move in a general westerly direction on the north face of the subtropical ridge.

A suspicious low is also present within the MT in the Australian' AoR, near from the Cocos Islands. This low-level circulation is expected to encounter mid-level dry and weak wind shear from the East to Northeast. Also, the development of this system should be rather slow at first. Next weekend, it could enter in our basin but encounter weak low level convergence conditions, with poor polar feeding, and an absence of equatorial flow. The mid-level dry air will remain aloft. Only a good upper level divergenc
e could give back strength to this system, in the beginning of next week, in front of a upper trough.

South of the Chagos, the risk of formation of a moderate tropical storm becomes moderate from Thursday and strong Saturday.

Over the extreme East of the basin, the risk of formation of a moderate tropical storm becomes low from Saturday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

037
AWIO20 FMEE 141245

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/14 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern east of 60oE. Under the influence of several equatorial waves (Rossby,...), the convective activity remains strong especially on the northern side of the MT and around two low pressure areas: one in the Australian AoR and one south of Diego Garcia.

Large low-pressure area south of the Chagos:

Since yesterday, the convective activity has fluctuated a lot in the region, and the maximum of vorticity monitored yesterday seems to have disappeared. Microwave images and this morning's Scatsat swath also seemed to indicate a new location of vorticity around 13.6S/75.7S but this too seems to have disappeared. This afternoon, convective activity seems to be organised around a mid-level circulation around 11.9S/73.4E but the latest microwave images (GMI 1005Z) do not show any significant curvature in the l
ow levels. In this context, combined with an poorly efficient convergence on the equatorial side, the risk of cyclogenesis in the next 24 hours seems rather low.

By the end of the weekend, this low will evolve into increasingly favourable environmental conditions. The low level convergence on the polar side will strengthen on Saturday and improve on the equatorial side. In upper levels, moderate easterly then north-easterly shear should remain present over the next 48 hours before weakening on Saturday under the upper ridge. The upper divergence should also significantly strengthen in the north-western quadrant on Saturday.

A cyclogenesis seems therefore likely during the weekend. The numerical models are in good agreement with this scenario but differ on the timing of this intensification. At longer range, while moving westward, this system could threaten inhabited lands especially Madagascar.

West of the Chagos, the risk of a moderate tropical storm is low tomorrow Friday, becomes moderate on Saturday and then high on Sunday.

In the Australian area :

A low pressure circulation is present around 13.1S 96.8E according to the latest Tropical Cyclone Outlook for the Western Region at 05UTC in a sheared environment. It could intensify in the next few days as it approaches our area of responsibility with the temporary drop in shear. It should cross 90E on Sunday in a still conducive environment. Thereafter, the environmental conditions should clearly deteriorate with the arrival of a strong west-north-westerly shear early next week ahead of an upper trough.

On the extreme East of the basin, the risk of formation or entry of a moderate tropical storm becomes moderate from Sunday onwards.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

129
AWIO20 FMEE 151243

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/15 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil but warnings WTIO20 and WTIO30 to be issued at 18Z, on Zone of Disturbed Weather 07-20202021.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) pattern east of 60oE. Under the influence of several equatorial waves (Rossby,...), the convective activity remains strong especially on the northern side of the MT and around two low pressure areas: one in the Australian AoR and one south of Diego Garcia.

Zone of disturbed weather 07-20202021, south-west of the Chagos:

Since yesterday, convective activity is mainly present in the western semicircle of a large surface low pressure circulation under the influence of a strong east-northeasterly shear. ASCAT and Scatsat swaths confirm this with maximum winds close to 25kt far from the center in the southern semicircle.

This weekend, this low will evolve into increasingly favourable environmental conditions. The low level convergence will improve on the equatorial side. In upper levels, is expected to weaken progressivly under the upper ridge. The upper divergence should also significantly strengthen in the north-western quadrant on Saturday.

A cyclogenesis seems therefore likely during the weekend. The numerical models are in good agreement with this scenario but differ on the timing of this intensification. Early next week upper conditions may deteriorate with an increasing north-easterly shear. However latest numerical guidance still suggest a deepening onwards probably due to the swift movement in the same direction as shear. This system could threaten inhabited lands especially Madagascar eastern coastline in the middle of next week.

West of the Chagos, the risk of a moderate tropical storm is moderate on Saturday and then high on Sunday.

Tropical Depression in the Australian area :

A tropical depression is monitored by the BOM near 15.1S 95.2E according to the latest IDW27600 (Tropical Cyclone Technical Bulletin) at 06UTC, in a sheared environment. It is expected to intensify in the next few days as it approaches our area of responsibility with the temporary shear decrease. It should cross 90E during the day on Sunday or the following night in a still favorable environment. Thereafter, the environmental conditions should clearly deteriorate with the arrival of a strong west-northwest
shear at the beginning of next week in front of an upper trough.

On the extreme East of the basin, the risk of formation or entry of a moderate tropical storm becomes moderate from Sunday onwards.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

488
AWIO20 FMEE 161121

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/16 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 no003/7 and WTIO30 no3/7/20202021 issued at 06Z on tropical depression no07-20202021.

Next warnings at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is established over the entire basin. The convective activity over the basin is essentially present within the clockwise circulation of tropical depression no07 and within the tropical low present in the Australian zone. Rainstorm activity, without the presence of a suspicious zone, is located in the North and North-West of Madagascar.

Tropical depression no07-202021 :

Position at 09Z: 12.5oS / 65.6oE
Max wind over 10 minutes: 30 kt
Central pressure: 998 hPa
Current motion: West-Southwestwards at 8 kt

For more information, please refer to the bulletins issued at 06Z and followings.

The risk of this system becoming a moderate tropical storm becomes high from Sunday onwards.

Tropical low in the Australian zone :

A tropical low continues to be tracked by the BOM around 16.6S 92.5E according to the latest Tropical Cyclone Technical Bulletin (IDW27600) of 06UTC. This system is still intensifying and is expected to reach 90E late next night or Sunday, potentially as a severe tropical storm. Thereafter, environmental conditions are expected to deteriorate significantly as vertical wind shear increases early next week.

On the extreme east of the basin, the risk of a tropical storm entering is very high from Sunday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

576
AWIO20 FMEE 181055

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/18 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 and WTIO30 n/11/7/20202021 issued at 06Z on moderate tropical storm no07 ELOISE.

Warnings WTIO20 and WTIO30 n/4/8/20202021 issued at 06Z on moderate tropical storm no08 JOSHUA.

Next warnings at 12Z.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is well established at the equator over the whole basin. It converges well with the clockwise circulations associated to the two tropical systems currently located over the basin. Convection is mainly located around ELOISE and JOSHUA but also within the slowing area of the monsoon flow between 65E and 85E.

Moderate Tropical Storm no07 ELOISE :

Position at 09Z: 14.1oS / 55.6oE
Max wind over 10 minutes: 40 kt
Central pressure: 993 hPa
Current motion: West Southwestwards at 14 kt
For more information, please refer to the bulletins issued at 06Z and followings.

Moderate Tropical Storm no08 JOSHUA :

Position at 09Z: 19.4oS / 86.8oE
Max wind over 10 minutes: 40 kt
Central pressure: 994 hPa
Current motion: West Southwestrwards at 6 kt
For more information, please refer to the bulletins that will be issued at 12Z and followings.

coming from the

From the middle of next week, some members of the european ensemble and even some deterministic model runs are suggesting the entrance of a new tropical storm on the East of the basin, coming from the australian AoR. Given the forecast guidance currently available,
the risk that a new tropical storm enters the basin from the East is deemed very low from Friday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

998
AWIO20 FMEE 201044

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/20 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 and WTIO30 no19/7/20202021 issued at 06Z on Overland Depression no07 ELOISE.

Next warnings issued at 12Z.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is well established at the equator West of 48E and East of
6E.

It converges mainly with the ELOISE's circulation, currently located over northern Madagascar.

A Monsoon Trough (MT) is located around 9S between 64E and the Eastern end of the basin.

The convection activity is mainly concentrated around the overland depression ELOISE, near the filling low JOSHUA and the northern part of the monsoon
rough.

Overland depresion no07 ELOISE :

Position at 09Z: 15.7S / 47.3E

Max wind over 10 minutes: 30 kt

Central pressure: 998 hPa

Current movement: West at 12 kt
For more information, please refer to the bulletins issued at 06Z and
ollowing.

Filling low no08 JOSHUA :

Position at 09Z: 21.6oS / 79oE

Max wind speed over 10 minutes: 25kt in the South quadrant.

Central pressure: 1008 hPa

Current movement: West 12 kt

It's going to track in a general west-southwest direction on the northern edge of the subtropical ridge, finishing filling up in the next few days.

Beyond the present forecast, the latest ensemble and deterministic models detect a suspicious zone, currently located in the Australian AoR. The last guidances see the possible coming of a new tropical storm on the extreme East of our AoR during the second half of next week.

The timing is still very uncertain at these ranges, and the numerical models remain quite divergent to propose a solid scenario.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Monday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
ext
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

343
AWIO20 FMEE 210952

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/21 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 and WTIO30 no24/7/20202021 issued at 06UTC on moderate tropical storm no07 ELOISE.

Next warnings issued at 12UTC.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a monsoon trough configuration centered from 7oS/50oE to 13oS on the eastern end of the basin. This configuration induces a well-established monsoon flow west of 50E which notably feeds the northern part of ELOISE. The convective activity is mainly concentrated around the moderate tropical storm ELOISE and at the eastern end of the basin, on the western part of a circulation currently over the Australian basin. Weak to moderate convective activity is also noticeable in the southeastern secto
r of the remnant low JOSHUA, located around 23oS/76oE.

Moderate tropical storm no07 ELOISE :

Position at 09UTC: 16.8S / 42.5E

Max wind over 10 minutes: 40 kt

Central pressure: 992 hPa

Displacement: West-South-West at 12 kt
For more information, please refer to the bulletins issued at 06UTC and following.

The latest ensemble and deterministic models detect a suspicious area, currently located in the Australian area of responsibility. The latest guidance forecasts the possible entry of this new tropical storm on the extreme east of our area of responsibility during the second half of next week.

The timing is still very uncertain at these times, and the numerical models remain quite divergent to propose a solid scenario.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Tuesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

343
AWIO20 FMEE 210952

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/21 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 and WTIO30 no24/7/20202021 issued at 06UTC on moderate tropical storm no07 ELOISE.

Next warnings issued at 12UTC.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a monsoon trough configuration centered from 7oS/50oE to 13oS on the eastern end of the basin. This configuration induces a well-established monsoon flow west of 50E which notably feeds the northern part of ELOISE. The convective activity is mainly concentrated around the moderate tropical storm ELOISE and at the eastern end of the basin, on the western part of a circulation currently over the Australian basin. Weak to moderate convective activity is also noticeable in the southeastern secto
r of the remnant low JOSHUA, located around 23oS/76oE.

Moderate tropical storm no07 ELOISE :

Position at 09UTC: 16.8S / 42.5E

Max wind over 10 minutes: 40 kt

Central pressure: 992 hPa

Displacement: West-South-West at 12 kt
For more information, please refer to the bulletins issued at 06UTC and following.

The latest ensemble and deterministic models detect a suspicious area, currently located in the Australian area of responsibility. The latest guidance forecasts the possible entry of this new tropical storm on the extreme east of our area of responsibility during the second half of next week.

The timing is still very uncertain at these times, and the numerical models remain quite divergent to propose a solid scenario.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Tuesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

775
AWIO20 FMEE 221050

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/22 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO20 and WTIO30 no27/7/20202021 issued at 06UTC on severe tropical storm no07 ELOISE.

Next warnings issued at 12UTC.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a monsoon trough configuration. It is centered from 7oS/55oE to 12oS on the eastern end of the basin. The resulting monsoon flow is well established west of 55E and feeds a low to moderate convective activity on the northern side of this trough. The rest of the weak to moderate convective activity is focused along a pseudo-warm front extending from the Seychelles to the west of Reunion Island, which is weakening. The main convective activity in the basin is focused near the severe tropical s
torm ELOISE.

Severe tropical storm no07 ELOISE :

Position at 09UTC: 19.2S / 37.6E

Max wind over 10 minutes: 60 kt

Central pressure: 986 hPa

Displacement: West-South-West at 12 kt
For more information, please refer to the bulletins issued at 06UTC and following.

Currently followed by the BOM via bulletin IDW27700, the moderate tropical storm (following the terminology of our basin) 10U presents a risk of entering our basin in the middle of next week, according to the forecasting of certain guidances.

The timing is still very uncertain at these deadlines, and the certain numerical models do not confirm in this re-entry.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Wednesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

747
AWIO20 FMEE 231053

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/23 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO24 and WTIO30 no31/7/20202021 issued at 06UTC on moderate tropical storm no07 ELOISE.

Next warnings issued at 12UTC.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is well established on the entire basin. However, trade winds remain weak over the central part of the basin, which does not define a clear monsoon trough pattern by lack of poleward convergence. The convective activity is mainly concentrated around ELOISE which made landfall on Mozambique last night. East of the basin, a weak system is located in the australian AoR.

Overland Depression no07 ELOISE :
Position at 09UTC: 20.6S / 33.6E
Max wind over 10 minutes: 35 kt
Motion: West-South-Westward at 9 kt
For more information, please refer to the bulletins issued at 06UTC and following.

Currently monitored by BOM through the IDW27700 bulletin (Tropical Cyclone Outlook), the tropical depression (according to the SWIO classification) 10U is currently affected by a moderate Easterly shear. It could enter our basin from the middle of next week. However, some models as well as some ensemble members still suggest a later entrance. Futhermore, mid-level dry air and the persistance of a weak upper Easterly shear constraint are rather unconducive for reintensification in the mid-term.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Wednesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

109
AWIO20 FMEE 241049

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/24 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO30 no35/7/20202021 issued at 06UTC on the overland depression no07 ELOISE.

Next warnings issued at 12UTC.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is well established on the entire basin. However, trade winds remain weak over the central part of the basin, which does not define a clear monsoon trough pattern by lack of poleward convergence.

The convective activity is mainly concentrated around ELOISE which now operates on land in northern South Africa close to the borders with Zambabwe and Botswanamade.

East of the basin, a weak system is located in the australian AoR.

Overland Depression no07 ELOISE :
Position at 09UTC: 23.1S / 29.8E
Max wind over 10 minutes: 25 kt
Pression : 998 hPa
Motion: South-Westward at 11 kt
For more information, please refer to the bulletins issued at 06UTC and following.

Currently monitored by BOM through the IDW10800 bulletin (Tropical Cyclone Outlook), the tropical depression (according to the SWIO classification) 10U is currently affected by a moderate Easterly shear. It could enter our basin from the middle of next week. However, some models as well as some ensemble members still suggest a later entrance. Futhermore, mid-level dry air and the persistance of a weak upper Easterly shear constraint are rather unconducive for reintensification in the mid-term.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Wednesday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

137
AWIO20 FMEE 251210

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/25 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Warnings WTIO30 no39/7/20202021 issued at 06UTC on the overland depression no07 ELOISE.

Last warning for this system.



PART 2 :
TROPICAL WEATHER DISCUSSION:


The monsoon flow is well established west of 56.5E, and remains less pronounced over the rest of the basin, where it is more zonal in orientation. The lower level convergence on the polar eastern side remains weak, due to the weakness of the ridge centered on the southeast side of the basin. Thus, it's quite difficult for the moment, to draw a clear monsoon trough axis. This will be easier in the end of the week.

The convective activity is rather weak now around ELOISE Overland Depression, which is currently evolving on land near the border between South Africa and Botswana. On the other hand, convective activity is moderate to fairly strong over the northern part of the MT, over the extreme eastern part of the basin and also near a tropical disturbance that is currently evolving 700 km southwest of the Eastern Coco Islands in the Australia's AoR.

Overland depression no07 ELOISE :

Position at 1030UTC: 24.2S / 25.2E

Max wind over 10 minutes: 15 kt

Pressure: 1007hPa.

Current movement: West-South-West at 14 kt
For more information, please refer to the bulletins issued at 06UTC.

Currently monitored by the BOM through the IDW10800 bulletin, the tropical disturbance (in the terminology of our basin) located at 0600Z by 17.4S - 95.9E, is under the influence of a moderate eastern wind shear that weakens it. On the other hand, it is offset by a good lower level convergence on the polar side.

It could enter our basin in the middle of next week. However, some numerical models still suggest a later entrance. In addition, mid-level dry air and the persistence of a weak Easterly shear aloft should hinder a possible re-intensification in the medium range.

Also, according to this analysis, the risk of a new tropical storm entering the extreme East of the basin is considered low as of Wednesday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

675
AWIO20 FMEE 261221

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/26 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The transequatorial monsoon flow is established over the whole width of the basin, rapidly shifting to westerlies between the equator and 10S. Low level convergence is weak on the polar side of the monsoon trough centered around 10/12S because of a weak and poorly organized trade wind regime caused by a a weak subtropical ridge.

The overall convective activity is weak across most of the basin and is mainly present north of 10S, although slightly enhanced near the Seychelles, in the Mozambique Channel as well as on the extreme northeastern side of the basin.

Overland depression no07 ELOISE :

The remnant low associated with ELOISE is still observed inland over southern Africa close to the border between South Africa and Botswana (the surface low was centered around 25.6S/22.9E this Tuesday at 09Z). The associated convective activity will continue to bring significant rainfall over the next 24 to 48 hours, particularly in north-central South Africa (over 100mm in 24 hours locally).

Tropical depression near the eastern border of our basin :

A tropical low monitored by the BOM is present in the Australian AoR, located near 18.5S/95.0S at 06Z this Tuesday (see IDW10800 bulletin). Its structure has improved this Tuesday afternoon due to a substantial decrease of the deep-layer wind shear (only 10kt) and to sufficient moisture surrounding the system.

These environmental conditions, combined with a good low-level convergence on the polar side of the system, are conducive for development in the very short run (next 24 hours or so).

Nevertheless, some dry air intrusions should occur from Wednesday, which should gradually weaken the system by the time it enters the SWIO AoR at 90E around Wednesday afternoon. At that time it could still be at tropical depression or tropical storm strength. On the southern side of the system, between 20S and 23S, winds should blow at near-gale to gale strength at least for Wednesday and Thursday.

With the subtropical high building up as from Wednesday, the easterly flow in which this system is evolving will accelerate, making it track faster in a west to west/north-west direction. On this track, the system should remain at a low to very low intensity (disturbance or tropical depression), still inhibited by a too dry and sheared mid-troposphere until Friday or Saturday.

During the weekend, NWP guidance shows a possibly more moist environment surrounding the system. Despite a persisting easterly shear, convection could be enhanced by some significant upper-level divergence on its western side. This could enable some intensification up to tropical storm strengh around Sunday to the north-east of the Mascareignes archipelago (between 60 and 70E and close to 15S). However, this remains a low probability option and there is no consensus in the panel of deterministic and ensembl
e models available.

The risk of a new tropical storm entering the extreme East of the basin becomes moderate on Wednesday.

After a weakening phase forecast in mid and late week, the risk of this system developping into a tropical storm to the north-east of the Mascareignes becomes low on Sunday.



NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

013
AWIO20 FMEE 271110

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/27 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Next warnings WTIO20 and WTIO30 no01/09/20202021 issued at 12UTC on tropical depression no09.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The major part of the basin is in a monsoon trough pattern, with a monsoon trough centered around 10/13S. On its equatorial side, the transequatorial monsoon flow rapidly shifts to westerlies between the equator and 10S. On its polar side, low level convergence remains weak due to a weak trade wind regime between 15S and the Tropic, on the northern edge of a poorly organised subtropical ridge. The latter should reconstitute more frankly to the southwest of the Mascarene Islands next weekend.

Convective activity associated with the ITCZ is mainly present north of 10S and east of 47E and generally weak over the remaining part of the basin. However, there is still strong rain and thunderstorm activity in the southeastern periphery of the remnant low ELOISE located over northern South Africa, but this activity is becoming increasingly dissociated from the depression itself and is being shifted quite far to the southeast of it. Indeed, a strong baroclinic interaction on the edge of a trough circulat
ing south of South Africa is triggering frontogenesis over southeastern South Africa, extending over the Southern Ocean further southeast where a baroclinic cyclogenesis should form between Wednesday evening and Thursday in the vicinity of 32/35S and 35/40E at the warm entrance of a powerful high-altitude jet stream, but without any risk that this depression will take on tropical characteristics.

Moreover, a new low pressure system is approaching the SWIO basin from the east this Wednesday, around 20S, coming from the Australian AoR (see below).

Tropical Depression 09 on the eastern edge of the basin (entering our area of responsibility) :
Position at 09UTC: 19.6S/91.1E
Estimated minimum pressure: 1001hPa
Max winds over 10 minutes: 30kt
Movement: West-Southwest at 7kt

For more information, please refer to the next bulletins issued.

Over the next five days, there is no risk of another moderate tropical storm forming in our basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

072
AWIO20 FMEE 281112

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/28 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Next warnings WTIO20 and WTIO30 no02/09/20202021 issued at 12UTC on tropical depression no09.

Last issues for this system.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin remains in a monsoon trough (MT) pattern over most of the northern part of the basin.

The MT is centered around 12/13S, with a monsoon flow turning rapidly to the West sector between the equator and 6S on the MT's equatorial side. On the polar side, the lower level convergence remains weak in connection with weak trade winds flow between 15S and the Tropic of Capricorn, north of a subtropical ridge of low troposphere fragmented and not very intense. This should reconstitute more strongly southwest of the Mascarene Islands as of next weekend.

The convective activity of the ITCZ is present in the basin over multiple
ones:

- In the area of slowing transequatorial flow, on the northern edge of the MT, between the equator and 4S, east of 68E.

- In the zone of slowing monsoon flow, in the northern Mozambique Channel, west of the Malagasy coast.

- In the western end of the TM between 10/18S and 60/68E, due to the altitude dynamics, which presents a warm jet inlet that instabilizes the warm air of the lower layers. This same dynamic, due to the presence of its cold air aloft, generates deep convection in the Mascarene area.

Tropical Depression no09 at the eastern end of the basin:

Position at 10UTC: 18.2S/85.3E

Estimated minimum pressure: 1003hPa

Max wind over 10 minutes: 30kt

Currently movement: West-Northwest at 15kt

For more information, please refer to the next bulletins issued at 12Z (the latest bulletins for this system)

Over the next five days, there is no risk of another moderate tropical storm forming in our basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
e
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

382
AWIO20 FMEE 291211

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/29 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a monsoon trough (MT) pattern over most of the northern part of the basin.

The MT is centered around 11/12S, with a monsoon flow turning westerly between the equator and 7S on the MT's equatorial side. On its polar side, the LL convergence has slightly increased since yesterday with a better organized trade winds flow north of a rebuilding LL subtropical ridge south of 30S. Low no09 is embedded in the MT and is drifting westward while gradually weakening.

Filling Low no09 :
Position at 1030UTC: 17.4S/77.9E
Estimated minimum pressure: 1006hPa
Max wind over 10 minutes: 20/25kt, reaching 30kt quite far from the center in the southern quadrant due to gradient effect.
Current movement: West at 17kt

This weak system is currently being sheared by a moderate easterly deep-layer shear and surrounded by dry air in the mid-troposphere. Although LL convergence is good on the trade wind side, it is very badly organized on the equatorial side of the system. Over the next days, model guidance forecasts that these unfavorable conditions will persist at least until Monday or Tuesday in the vicinity of the system while it drifts westward, which will continue to keep it weak or even make it weaker. From Tuesday, ea
sterly shear should ease a bit and upper divergence could slightly increase under the influence of a subtropical upper-level trough circulating south of the system. Besides, LL convergence is expected to improve equatorward. Consequently, some model runs suggest a risk of intensification in the longer run.

Over the next five days, there is no risk of a moderate tropical storm forming in our basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

833
AWIO20 FMEE 301153

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/30 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin remains in a monsoon trough (MT) pattern over most of the northern part of the basin.

The MT is centered around 11/12S, with a monsoon flow turning westerly between the equator and 7S on the MT's equatorial side. On its polar side, the LL convergence is good on the northern side of the anticyclone. Filling Low no09 is embedded in the MT and is drifting westward while gradually weakening.

Filling Low no09 :
Position at 1030UTC: 16.2S/70.4E
Estimated minimum pressure: 1006hPa
Max wind over 10 minutes: 20/25kt, reaching 30kt quite far from the center in the southern quadrant due to gradient effect.
Current movement: West-North-West at 14kt

Over the next days, model guidance forecasts that unfavorable conditions will persist while drifting westward, which will continue to keep it weak or even make it weaker. Equatorial convergence is expected to remain quite weak preventing from any significant risk of deepening. Early next week, the low will probably merge with the MT, and so dissipate.

Over the next five days, there is no risk of a moderate tropical storm forming in our basin.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

618
AWIO20 FMEE 311127

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/01/31 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:

The basin remains in a Moonson Trough (TM) pattern East of 48E and is centered around 11/12S. It benefits from a good lower level convergence on the equatorial side, between 48E and 80E. The monsoon flow East of 80E turns rapidly westerly between the equator and 9S. On the polar side, the trade winds remains well present on the northern side of the subtropical ridge.

Within the MT, filling low no9, currently located 920 km from Reunion Island, is being drifting west-northwesterly, while gradually weakening.

Convective activity is mainly observed in the slowing of the monsoon flow north of the MT, as well as in the southern quadrant of the filling depression no9.

Filling depression no09 :

Position at 0930UTC: 14.9S/61.7E

Estimated minimum pressure: 1007hPa

Max wind over 10 minutes: 20/25kt away from the center in the South and Southeast quadrant by gradient effect.

Current movement: West-Northwest at 20kt

For the next five days, this low depression will track west-Northwesterly. Deterministic and ensemble models suggest unconducive conditions for its development, which should keep it weak or event make it weaker. The system should thus dissipate in the first part of next week.

In the second half of next week, the main guidances detect a suspicious low, within the TM, on the extreme North-East of the basin. At this point, the timing remains uncertain for the moment, and the models remain divergent to propose a solid scenario.

Also, According to the latest analysis, the risk of a new tropical storm entering the extreme East of the basin is considered very low as of Friday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

723
AWIO20 FMEE 021111

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/02/02 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) east of 55E, centered around 10/11S. Good low-level convergence is present on its equatorial side . On the polar side of the TM, low-level convergence remains well marked on the north face of the subtropical anticyclone.

Within the TM, Depression No. 9, located about 860 km from Reunion Island, is currently drifting west northwestward and gradually filling.

The convective activity is mainly observed in the slowing of the monsoon flow north of the TM, east to 73E south of the TM as well as in the northwestern quadrant of the filling depression no9.

Filling depression no09 :

Position at 1000UTC: 13.0S/53.6E

Estimated minimum pressure: 1009hPa

Max wind over 10 minutes: 20kt far from the center, in the South quadrant by gradient effect.

Movement: West northwest at 10kt

For the next five days, this system will continue on a course towards the West-Northwest then northwest. Deterministic models suggest unfavourable conditions for its development, which should continue to weaken this already fragile circulation. The system is expected to dissipate by the end of week.

This weekend, some guidances detect a suspicious area on the extreme east of the basin, within the TM. However, models diverge about the timing and environmental conditions linked to this system. For the moment, chances of development remain very low.

The risk of a new tropical storm forming over the extreme east of the basin is considered very low as of Friday and low on Sunday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

440
AWIO20 FMEE 031123

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/02/03 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a Monsoon Trough (MT) east of 50E, centered around 11/12S. It benefits from a good supply of low level convergence East of 71E, with a good equatorial convergence. On the polar side of the MT, the low level convergence remains well defined on the north side of the subtropical ridge.

Within the MT, northeast of Cap d'Ambre, Depression Number 9, located about 1150 km from Reunion Island, is currently tracking west-northwesterly, gradually filling up.

The convective activity is mainly observed in the slowing of the monsoon flow, north of the TM, as well as south of the MT east of 75E, in the northwestern and southern quadrant of the filling depression number 9 and in the north of the Mozambique Channel due to local low level convergences.

Filling Depression No. 9:

Position at 0900UTC: 11.9S/52.1E

Estimated minimum pressure: 1010hPa

Max wind over 10 minutes: 15kt away from the center in the South quadrant by gradient effect, according to the swath of this morning (Scat-Sat).

Current movement: West northwest at 7kt

For the next five days, this low will track West-Northwesterly. Numerical weather prediction suggest unconducive environmental conditions for its development, which should continue to weaken an already weak low level circulation. This system is expected to dissipate by the weekend.

Over the weekend, the main numerical guidance detect a suspicious area in the extreme east of the basin, nested in the monsoon trough. The timing remains unsure for the moment, and the numerical guidance remain divided to suggest a reliable consensus.

Thus, according to the latest analysis, the risk of a new tropical storm forming over the extreme east of the basin is considered low as of Friday.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

452
AWIO20 FMEE 041130

TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN

DATE: 2021/02/04 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil.

PART 2 :
TROPICAL WEATHER DISCUSSION:


The basin is in a well-defined monsoon trough (MT) pattern along 10S. Convection is mainly located on the equaorial side of the MT, within the slowing area of the monsoon flow. While the system nb 09 merged with the Western tip of the MT, a new clockwise circulation developed South-East of the Chagos.

A well-defined surface circulation appeared as a low-level clouds vortex on this morning sat animations, near 11.45S/81E at 06Z. This circulation begins to concentrate significant convective activity, while benefiting from conducive conditions currently : a nice monsoon feed in the low-levels and a good upper divergence aloft. Max winds are estimated at 20kt on each side of the circulation.

However, the environment is expected to become more neutral with decreasing low-level convergence and upper divergence. The available guidance also have mixed feelings about this environment and do not translate it as a deepening in every model run. The ensemble prediction illustrate this uncertainty with a moderate risk of cyclogenesis.

The risk of formation of a moderate tropical storm becomes moderate from Sunday South-East of the Chagos.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and within the next five days:

Very low: less than 10% Moderate: 30% to 60% Very high: over 90%
Low: 10% to 30% High: 60% to 90%

The Southwestern Indian Ocean basin extends from the equator to 40S and from the african coastlines to 90E.
--- SBBSecho 3.12-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)